Manufacturing-process profiles: design rules by process, and the experts behind them (2026-10-31)

For Valpatel/cad-agent #99 (process profiles), #118 (cite every rule by name), #97 (pitfall checks) and #95 (calculators). The machine-readable twin of this page is process-profiles.yaml: every rule below is a row there, with an id, a value or an expression, units, its source and the date it was read.

What the part is made by decides what it may look like. This page collects the design rules that manufacturers, fabricators, standards bodies and named engineers publish for FDM, resin and powder printing, injection moulding, sheet metal and CNC, says where they disagree, and credits each one to the person or company behind it. We are highlighting experts, not taking credit for their tips: every rule names its source and links to it, and nothing is copied.

How this was checked. "Read" means the number was seen in the source's own text on 2026-10-31 (the page's HTML, the PDF through pdftotext, an Internet Archive copy where the live page blocks scripts, or, for two DuPont figures with no text layer, the rendered figure; the YAML says which). (u) marks anything not verified, and the YAML gives it status: u so no check enforces it. [derived] means we calculated it from cited numbers; the method is stated. Inches are converted at 25.4 mm and the printed value kept in the YAML (as_printed). Paid standards are cited by number and title only.

Range chart of the minimum wall thickness each source recommends, grouped by process

1. Reading the rules

A shop's own table beats every generic rule. Sheet-metal radius, K-factor and minimum flange come from the shop's tooling (§7); a printer's walls come in whole perimeters (§2). The generic rules are the fallback when the shop or machine is not chosen yet, and a check should say which one it used.
A rule is only as good as its datum. Hole-to-bend distances are measured from the bend line, the tangent, the inside face or the hole's edge, depending on who wrote them (§7). The YAML has a datum field for this.
Limits are written once, as numbers or expressions. min: "2*T + R" means at least twice the thickness plus the bend radius; value: "max(0.005*L, 0.5)" is ±0.5 % of the dimension with a ±0.5 mm floor. tools/process_profile_figures.py has the evaluator, and the tests evaluate every expression.
Rules that compare share a compare key (min-wall, sm-hole-to-bend, …). The charts on this page are drawn from those keys, so a rule added to the YAML appears in its chart on the next run.

2. FDM / FFF (material extrusion)

Orientation and anisotropy

The data is already on compliant-mechanisms.md §5–6 (13 filaments from Bambu Lab and Polymaker data sheets, and HP's MJF data), and is not repeated here. In short: across the layers, strength is 0.40–0.90 of the in-plane value but strain to failure only 0.10–0.61, so anything that flexes (snap arms, clips, springs, hinges) lies in the build plate's plane, and bending across the layers is avoided.

Rule	Value	Applies when	Source
Lay flexing and brittle features parallel to the build plate	Z strength 0.40–0.90 × XY; Z strain 0.10–0.61 × XY	Data sheets, 100 % infill	compliant-mechanisms.md §5
A cantilever snap built along Z is poor; the stair-step adds notches	qualitative	Printed snap fits	Christoph Klahn, Daniel Singer and Mirko Meboldt, Procedia CIRP 2016
FDM parts are weakest along Z; layer joints are small valleys that concentrate stress	qualitative	All FDM	Protolabs Network

Overhangs and bridges

Rule	Value	Applies when	Source
Steepest unsupported overhang, from vertical	≤ 45°	Most materials	Protolabs Network; Xometry Europe
Steepest clean overhang, from vertical	45–60°	0.4 mm nozzle, by settings; a 0.25 mm nozzle may manage less	Prusa Research
Steepest overhang with 360° part cooling	≤ 75°	Prusa's Nextruder printers (MK4S, CORE One family)	Prusa Research
Longest bridge without sag or support marks	≤ 5 mm	Horizontal bridges and roofs	Protolabs Network; Xometry Europe
Chamfer rather than fillet an edge facing the bed	qualitative	A fillet facing down is a steep overhang	Prusa Research

Walls, holes, pins and corners

Rule	Value	Applies when	Source
Minimum wall	≥ 0.8 mm	Any printer in the network	Protolabs Network
Thinnest printable wall: one perimeter	0.45 mm (2: 0.9, 3: 1.35, 4: 1.8 mm)	0.4 mm nozzle in PrusaSlicer; a wall thinner than one perimeter does not print	Prusa Research
Minimum wall	0.75 mm supported, 1.0 mm unsupported, or 3 × nozzle	Xometry Europe's service	Xometry Europe
Minimum supporting wall	1.2–1.5 mm (0.047–0.06 in)	Xometry's industrial FDM	Joel Schadegg and Aaron Lichtig, Xometry
Smallest hole that stays round	≥ 1 mm (0.04 in)	Axis vertical prints best; critical holes drilled after	Joel Schadegg and Aaron Lichtig, Xometry
Vertical holes print undersize	measured 0.25 mm under CAD	One printer and PLA; print a coupon for yours. Drill critical holes	Stefan Hermann, CNC Kitchen; Protolabs Network
Vertical pins below this are perimeters only and weakly joined	5 mm	Smaller: fillet the base, or a hole and a bought pin	Protolabs Network
Minimum pin; minimum column	1 mm; 2–3 mm	Keep pins short	Xometry Europe
Outside corners in the layer plane	radius = nozzle diameter	Never sharp	Protolabs Network
Minimum rib	≥ 1.5 mm (0.06 in)	Several extrusions per rib	Joel Schadegg and Aaron Lichtig, Xometry
Embossed text stroke / engraved text stroke	≥ 0.8 mm (0.5 mm high) / ≥ 1.0 mm (0.5 mm deep)	Top faces read best	Xometry Europe

Elephant's foot and warping

Rule	Value	Applies when	Source
First-layer inset (elephant-foot compensation)	about 0.2 mm	0.4 mm nozzle, PrusaSlicer; on in Prusa's profiles	Prusa Research
Chamfer (or radius) on edges touching the bed	45°	Where fit or overall size matters; eases removal too	Protolabs Network
Typical shrinkage	0.2–1 %	By material; hotter materials warp more (bottom radius or brim)	Protolabs Network

Tolerances and clearances

Rule	Value	Applies when	Source
Expected tolerance	±0.5 %, floor ±0.5 mm	Desktop (prototyping) FDM	Protolabs Network
General tolerance	±0.5 % (±0.5 mm), as printed; the YAML reads the ±0.5 mm as a floor, which Xometry Europe's page does not state	Xometry Europe's standard and industrial machines (up to 900 × 600 × 900 mm)	Xometry Europe
Expected tolerance	±0.15 %, floor ±0.2 mm	Industrial FDM	Protolabs Network
Tolerance the service holds	±0.127 mm (±0.005 in)	Xometry's industrial FDM; no size dependence stated	Joel Schadegg and Aaron Lichtig, Xometry
Clearance between mating parts (snap fits)	0.5 mm	Protolabs Network FDM	Protolabs Network
Clearance for parts that move or snap	≥ 0.3 mm to start	Original Prusa printers, accurate to at least 0.2 mm; test-print	Prusa Research
Clearance for a sliding fit	0.2–0.3 mm	Mating faces printed vertical	Xometry Europe

Threads and inserts

Rule	Value	Applies when	Source
Smallest thread worth printing	M5	Below that: insert, tap or self-tapping screw	Protolabs Network
Wall around a thread or insert	≥ the fastener diameter (M5: 5 mm)	Rule of thumb	Protolabs Network
Offset around an embedded nut	0.2 mm total (0.1 per side)	Loose fit; more above M12	Protolabs Network
Self-tapping pilot hole	for 75–80 % thread engagement	When the screw maker gives no size	Protolabs Network
M3 heat-set insert hole, as built	4.0 mm; pull-out falls sharply above 4.1–4.2 mm	CNC Kitchen's M3 insert	Stefan Hermann, CNC Kitchen
Add to the insert hole in CAD	0.2–0.3 mm (M3 in PLA: 4.2 mm kept about 90 % of the best pull-out)	Small inserts; size so the insert pre-seats with slight resistance	Stefan Hermann, CNC Kitchen
Blind insert hole depth	insert length + about 1 mm; straight, not tapered, normally no chamfer	Through holes no longer than the insert	Stefan Hermann, CNC Kitchen
Iron temperature	printing temperature + 10–20 °C; melt 90 % in, press the rest	Resin parts: glue into a stepped hole instead	Stefan Hermann, CNC Kitchen

Where the FDM sources disagree

Minimum wall: 0.45 to 1.5 mm. Prusa's 0.45 mm is one perimeter, the physical floor; Protolabs Network's 0.8 mm and Xometry Europe's 0.75–1.0 mm are what a service will accept; Xometry's US guide asks 1.2–1.5 mm for a wall that carries load. They measure different things: printable, accepted, and strong. Design walls as whole perimeters.
Overhang: 45° to 75°. 45° is the conservative service rule. Prusa says 45–60° on a 0.4 mm nozzle and up to 75° with 360° cooling. The machine decides; the profile should carry the printer.
Tolerance: ±0.127 mm to ±0.5 mm. Xometry's US guide claims ±0.005 in flat. Protolabs Network gives ±0.5 % with a ±0.5 mm lower limit for desktop machines. Xometry Europe's table prints "±0.5 % (±0.5 mm)" for its standard and industrial machines without saying which governs; the YAML reads it as the same floor, which is our reading, not their text. At 50 mm the ±0.5 mm floor against Xometry's US figure is a factor of four [derived].
Clearance: 0.2 to 0.5 mm. Sliding fit 0.2–0.3 mm (Xometry Europe), moving parts from 0.3 mm (Prusa), snap fits 0.5 mm (Protolabs Network). Xometry Europe's page also gives "0.5 mm clearance for an interference fit", which reads as a slip (a clearance cannot make an interference fit); the YAML does not use it.
Insert holes. CNC Kitchen's own data sheet hole (4.0 mm for M3) is right for the hole as built; printed holes come out smaller, so the CAD hole is larger. Stefan Hermann published the test that shows this.

3. SLA and MSLA (resin)

This covers laser SLA (Formlabs Form 2 and Form 3, Protolabs, Materialise) and masked SLA on an LCD (Formlabs Form 4, Prusa SL1, and printers sliced in ELEGOO SatelLite or Lychee). Formlabs runs the same tests on three printers, which shows how much a resin rule depends on the machine:

Formlabs test	Form 2 (laser)	Form 3 / 3B (laser)	Form 4 (MSLA)
Minimum wall, supported or unsupported	0.4 mm	0.2 mm	0.2 mm
Unsupported overhang: angle from level; length	≥ 19°; ≤ 3.0 mm	≥ 10°; ≤ 5.0 mm	≥ 10°; ≤ 5.0 mm
Span between supports (beam 5 mm wide, 3 mm thick)	≤ 21 mm	≤ 29 mm	≤ 29 mm
Embossed detail; engraved detail	0.1 mm; 0.4 mm	0.1 mm; 0.15 mm	0.1 mm; 0.15 mm
Clearance between parts of one print	0.5 mm	0.5 mm	0.4 mm
Hole; drain hole for an enclosed cavity	0.8 mm; 3.5 mm	0.5 mm; 2.5 mm	0.5 mm; 0.75 mm
Test resin and layer	Clear, 100 µm	Clear, 100 µm	Grey, 50 µm
Source	Formlabs, Form 2	Formlabs, Form 3	Formlabs, Form 4 guide

Rule	Value	Applies when	Source
Tolerance, by feature size	±0.15 % to 30 mm (floor ±0.02 mm); ±0.2 % to 80 mm (floor ±0.06); ±0.3 % to 150 mm (floor ±0.15)	Form 4 generation, Grey resin at 100 µm, three printers	Formlabs
LCD pixel size (the XY resolution)	50 µm	Form 4 is masked SLA; the Form 3 family is laser SLA	Formlabs
Drain holes per hollow cavity	≥ 2, one as close to the build platform as possible	Hollowing in PreForm or Meshmixer	Formlabs
Minimum wall; hole; X-Y feature	0.254 mm; 0.635 mm; 0.254 mm (Z 0.406)	Protolabs normal resolution; micro resolution goes to 0.0635 mm walls and 0.381 mm holes	Protolabs
X/Y tolerance	±0.05 mm + 0.1 % (Z ±0.127 mm + 0.1 %)	Well-designed parts	Protolabs
Minimum wall, supported / unsupported	0.4 / 0.6 mm		Niko Mroncz, Xometry Asia
Pin; slot	≥ 1 mm; ≥ 0.5 mm		Niko Mroncz, Xometry Asia
Clearance, moving parts and assemblies	≥ 0.5 mm (snug fit about 0.1 mm)		Niko Mroncz, Xometry Asia
Hollow wall; drain hole	≥ 2 mm; ≥ 3.5 mm, one per hollow section		Niko Mroncz, Xometry Asia
Unsupported overhang	≤ 2 mm long, ≥ 30°		Niko Mroncz, Xometry Asia
Corner radius	≥ 0.5 mm; inside ≥ half the wall, outside ≥ 1.5 × the wall		Niko Mroncz, Xometry Asia
Embossed; engraved; text	0.5 high × 0.4 wide; 0.5 × 0.5 mm; ≥ 1 mm tall, 2 mm better		Niko Mroncz, Xometry Asia
Tolerance	±0.5 % (±0.2 mm) standard, ±0.15 mm industrial	The YAML reads it as 0.5 % with a 0.2 mm floor	Niko Mroncz, Xometry Asia
Minimum wall, by size	1 mm (x + y + z under 200 mm), 2 mm (200–400 mm), 3 mm (larger)	Taurus	Materialise
Surfaces that need no support; ledges	≥ 30° (the rule of 30°); ≤ 2 mm	Inside and outside	Materialise
Hole for removing internal supports	≥ 10 mm	Hollow parts	Materialise
Text line and depth; accuracy	≥ 0.5 mm; ±0.2 %, floor ±0.2 mm		Materialise
Minimum wall, by footprint	0.5 mm (5 × 5 mm) to 2.0 mm (200 × 200 mm)	Resin	JLC3DP
Clearance, moving / assembled; escape hole	0.5 / 0.2 mm; ≥ 2.5 mm, two if under 3 mm		JLC3DP
Embossed or engraved; tolerance	0.8 × 0.8 mm; ±0.2 mm to 100 mm, ±0.3 % above	Parts drift a further 0.15–0.2 mm in the first week	JLC3DP
Hollow shell; drain holes	≥ 1 mm (the tool's floor); ≥ 2	SL1, SL1S (MSLA)	Prusa Research
Hollow wall; drain hole	1–3 mm; 2–6 mm across, ≥ 2 at the lowest point	ELEGOO SatelLite	ELEGOO
Hollow wall	2.5 mm default; 1.5–2 mm miniatures; 3–4 mm strong parts	Lychee Slicer	Mango3D (Lychee Slicer)

From Protolabs Network's SLA guide:

Rule	Value	Applies when	Source
Minimum wall, supported / unsupported	≥ 0.4 mm / ≥ 0.6 mm (fillet the base)	Supported: joined on at least two sides	Protolabs Network
Minimum wall	≥ 0.5 mm	SLA/DLP, cross-process table	Protolabs Network
Unsupported overhang	≤ 1.0 mm long and at least 19° from level	Only without supports (not advised)	Protolabs Network
Minimum hole	0.5 mm (table) or 0.8 mm (text)	The guide gives both; use 0.8 mm	Protolabs Network
Hollow wall; drain hole	≥ 2 mm; ≥ 3.5 mm, one per hollow section	Trapped resin causes cupping and cracks	Protolabs Network
Clearance: moving / assembly / snug	0.5 / 0.2 / 0.1 mm	Protolabs Network SLA	Protolabs Network
Clearance between mating parts (snap fits)	0.3 mm	Also SLS, MJF	Protolabs Network
Embossed detail; engraved detail	≥ 0.1 mm high; ≥ 0.4 mm wide and deep		Protolabs Network
Longest wide bridge	< 21 mm	Wide bridges peel harder	Protolabs Network
Expected tolerance	±0.5 %, floor ±0.10 mm (desktop); ±0.15 %, floor ±0.01 mm (industrial)		Protolabs Network

Where the resin sources disagree

Protolabs Network's numbers are Formlabs' Form 2 numbers. Its 19° overhang, 21 mm bridge, 0.4 mm engraving and 0.8 mm hole all match the Form 2 sheet (and so do its 3.5 mm drain hole and 0.4 mm supported wall); Form 3 and Form 4 are finer on almost every line. That may also explain its own 0.5 against 0.8 mm hole. A profile should carry the printer, not just "SLA".
Drain hole: 0.75 to 3.5 mm. 0.75 mm on Form 4, 2.5 mm on Form 3 and JLC3DP, 3.5 mm on Form 2, at Xometry and at Protolabs Network; ELEGOO says 2–6 mm. Materialise's 10 mm is for pulling supports out, not draining.
Minimum wall: 0.2 to 0.6 mm, or by size. Formlabs 0.2 mm (Form 3, Form 4), Protolabs 0.254 mm, Xometry and Protolabs Network 0.4 supported and 0.6 unsupported. Materialise (1–3 mm) and JLC3DP (0.5–2 mm) scale the wall with the part, which none of the others do.
Overhang: 1 to 5 mm, 10° to 30°. Formlabs 5 mm at 10°; Xometry 2 mm at 30°; Materialise a 2 mm ledge and the rule of 30°; Protolabs Network 1 mm at 19°.
Tolerance at 50 mm: ±0.1 to ±0.25 mm [derived]: Formlabs Form 4 ±0.1, Protolabs ±0.1, Materialise ±0.2, JLC3DP ±0.2, Xometry ±0.25 (and Protolabs Network ±0.25 desktop, ±0.075 industrial).
Formlabs against itself. The Form 3 support page gives a 2.5 mm drain hole and 0.5 mm clearance; the Form 4 guide's Form 3 column gives 0.75 mm and 0.4 mm and says the values "did not change". The tests differ (Clear resin at 100 µm against Grey at 50 µm); the YAML keeps both, each with its test.
Protolabs' high-resolution X-Y feature prints 0.005 in beside 0.1016 mm; 0.005 in is 0.127 mm. The YAML uses the normal-resolution row only.

4. SLS (polymer powder bed)

Rule	Value	Applies when	Source
Pin; hole	≥ 0.8 mm; ≥ 1.0 mm (most accurate with the axis along Z)	Fuse, Nylon 12	Formlabs
Unsupported wall	≥ 0.6 mm vertical; ≥ 0.3 mm horizontal	Fuse, Nylon 12	Formlabs
Escape holes	≥ 3.5 mm, at least two per cavity		Formlabs
Embossed; engraved, on a horizontal face	0.15 deep × 0.35 wide; 0.1 × 0.3 mm (vertical faces 0.35 × 0.4; 0.15 × 0.35)		Formlabs
Clearance, assembled after / printed together	0.2 / 0.3 mm for features under 20 mm², 0.4 / 0.6 mm above	≥ 1 mm printed together in Nylon 11 and TPU 90A	Formlabs
Lattice gap; space between parts	≥ 8 mm; ≥ 5 mm (tilt flat parts about 20°)	Depowdering in Fuse Sift; packing	Formlabs
Minimum wall; minimum feature	0.762 mm; 0.762 mm nylons, 1.01 mm PP and TPU		Protolabs
Tolerance	±0.25 mm + 0.1 %	Well-designed parts	Protolabs
Uniform thickness against warp	3.175 mm	Parts over 178 mm are most at risk	Protolabs
Channel gap; shell for a thick feature	≥ 0.762 mm; 2.54–3.175 mm	SLS and MJF	Protolabs
Minimum wall	0.5 mm (PA 12) to 2.0 mm by material; 1.5 mm for repeatable results		Niko Mroncz, Xometry Asia
Escape hole; hole	≥ 3.5 mm; ≥ 1.5 mm		Niko Mroncz, Xometry Asia
Clearance: mating / press fit / articulated	0.7 / 0.5 / 0.6 mm		Niko Mroncz, Xometry Asia
Pin; text	≥ 0.8 mm (1 mm better); 1 mm high or deep, font ≥ 2 mm		Niko Mroncz, Xometry Asia
Shrinkage to allow; tolerance	3–4 %; ±0.3 mm		Niko Mroncz, Xometry Asia
Tolerance	±0.381 mm or ±0.2 %, the greater (Nylon 12); ±0.508 mm or ±0.3 % (Nylon 11)	US service	Xometry
Minimum wall; living hinge	≥ 1 mm; 0.3 mm	PA 12	Materialise
Clearance, printed together / assembled after	0.5–0.6 / 0.6 mm		Materialise
Hole; internal channel	≥ 1 mm; ≥ 3 mm		Materialise
Walls the service may hollow; accuracy	above 9 mm (by default above 20 mm); ±0.3 %, floor ±0.3 mm		Materialise
Wall	0.45 mm (Formiga P100) to 0.7 mm possible; 1.5 mm for reproducible properties	XY	Franz-Josef Kerl, EOS (2011)
Pin	≥ 0.8 mm; 1.8 mm for reproducible properties		Franz-Josef Kerl, EOS
Gap: hinge printed in place / loose connection	0.3–0.5 mm in XY (Z at least three layers) / 0.1 mm		Franz-Josef Kerl, EOS
Faces to keep off the XY plane	angles under 20° show layer steps		Franz-Josef Kerl, EOS
Smallest gap or hole, rising with the wall (u)	0.5–0.8 mm for walls 0.3–6 mm	Read from a chart	Franz-Josef Kerl, EOS
Minimum wall, by footprint; clearance	1.0–2.0 mm; 0.2–0.4 mm	Nylon SLS	JLC3DP

From Protolabs Network:

Rule	Value	Applies when	Source
Minimum wall	0.8 mm (PA 12) to 2.0 mm (carbon-filled PA)		Protolabs Network
Minimum wall	≥ 0.7 mm	Cross-process table	Protolabs Network
Minimum hole; escape hole	> 1.5 mm; ≥ 3.5 mm	Hollow parts and enclosed clearances	Protolabs Network
Clearance	0.3 mm; 0.2 mm ball in socket; 2 mm round a running axle	So the powder can be cleared	Protolabs Network
Minimum feature; engrave and emboss	0.8 mm; 1 mm, text at least 2 mm high		Protolabs Network
Edge and corner radius as printed	0.4 mm; more than 2 mm where stress matters		Protolabs Network
Living hinge	0.3–0.8 mm thick, at least 5 mm long; anneal and flex	SLS nylon	Protolabs Network
Scale applied before printing	3–3.5 %	Done by the service	Protolabs Network
Expected tolerance	±0.3 %, floor ±0.3 mm	SLS and MJF	Protolabs Network

Where the SLS sources disagree

Minimum wall: 0.3 to 2 mm. Formlabs 0.3 mm horizontal and 0.6 mm vertical; Protolabs Network 0.7–0.8 mm; Protolabs 0.762 mm; Materialise 1 mm; JLC3DP 1–2 mm by size; Xometry 0.5–2 mm by material. Xometry (1.5 mm) and EOS (1.5 mm) give a second, thicker number for walls that must be repeatable or carry their full properties. As with FDM, these are printable, accepted and reliable.
Clearance printed together: 0.3 to 0.76 mm. Formlabs 0.3 or 0.6 mm by area, EOS 0.3–0.5 mm, Materialise 0.5–0.6 mm, Xometry 0.6 mm articulated, Protolabs 0.762 mm channel gaps. Assembled after printing: 0.1 to 0.7 mm: EOS 0.1 mm "loose", Formlabs 0.2–0.4, Materialise 0.6, Xometry 0.7 mm for mating parts.
Hole: 1.0 mm (Formlabs, Materialise) against 1.5 mm (Xometry, Protolabs Network). Escape hole: 3.5 mm (Formlabs, Xometry, Protolabs Network) against 2.5 mm (JLC3DP).
Tolerance agrees at about ±0.3 mm at 50 mm [derived]: Protolabs ±0.30, Materialise ±0.3, Protolabs Network ±0.3, JLC3DP ±0.3, Xometry US ±0.381.

5. HP Multi Jet Fusion

Rule	Value	Applies when	Source
Hole through a 1 mm wall; shaft 10 mm tall	≥ 0.5 mm; ≥ 0.5 mm	X, Y and Z	HP, MJF handbook
Clearance at 1 mm thickness; slit between walls	≥ 0.5 mm		HP
Detail width; embossed or engraved height	≥ 0.1 mm (letters ≥ 6 pt); ≥ 1 mm for the best result		HP
Long, thin, flat parts	length ≤ 10 × width	Warpage	HP
Short wall, XY / Z	≥ 0.3 / ≥ 0.5 mm	PA 12, PA 12 GB, PA 11	HP
Gap, assembled after / printed together	0.4 mm (±0.2 on each part) / ≥ 0.7 mm (0.3 mm if walls are under 3 mm)		HP
Hollow wall	≥ 2 mm		HP
Printed threads; tolerance machining adds	≥ M6 (else self-tapping screws or inserts); ±0.05 mm		HP
Tolerance at Cpk 1.33, up to 30 mm	XY ±0.30, Z ±0.42 mm (up to 80 mm: ±0.44, ±1.18)	Jet Fusion 5200, PA 11, default settings	HP
Wall; minimum feature	≥ 0.5 mm		Protolabs
Tolerance	±0.30 mm + 0.1 %	Well-designed parts	Protolabs
Wall that keeps tolerance and warp in check	2.5–12.7 mm		Protolabs
Knife edge	≥ 0.508 mm		Protolabs
Short wall, XY	≥ 0.3 mm (0.4 mm in Z)		Xometry Asia
Clearance, printed together / assembled after	0.7 / 0.4 mm	More for walls over 50 mm	Xometry Asia
Drain holes; lattice gap	2 mm, at least two; ≥ 1 mm		Xometry Asia
Tolerance	±0.2 mm to 100 mm, 0.2 % above	After sand-blasting	Xometry Asia
Minimum feature	0.508 mm (1.016 mm recommended)	US service	Xometry
Tolerance under 30 mm	XY ±0.25, Z ±0.42 mm after engineering review; ±0.70 mm without	HP 5200, rigid materials	Xometry
Wall; living hinge	≥ 1 mm; 0.5 mm, at most 10 mm long held at one end (25 mm at both)	PA 12	Materialise
Escape holes; hollowing	≥ 2 mm, at least two; hollow walls over 20 mm to 2–3 mm		Materialise
Hole; internal channel	≥ 1 mm (2 mm recommended); ≥ 3 mm		Materialise
Clearance, printed together / assembled after	0.5 / 0.6 mm		Materialise
Text; accuracy	0.5 mm line, 1 mm deep, 2.5 mm tall; ±0.3 %, floor ±0.3 mm		Materialise
Wall	0.5–3.0 mm	Thicker walls sink and warp	Stratasys Direct
Interior fillet; knife edge; living hinge	≥ 0.4 mm; ≥ 0.5 mm; ≥ 0.5 mm, annealed for more than a few cycles		Stratasys Direct
Bonded lap overlap; boss round an insert	3–5 × the wall; 2–3 × the insert diameter	Heat staking preferred	Stratasys Direct
Tolerance	±0.25 mm or ±0.1 %, the greater		Stratasys Direct
Minimum wall, by footprint; tolerance	1.0–2.0 mm; ±0.3 mm to 100 mm, ±0.4 % above	Nylon MJF	JLC3DP
Minimum wall	≥ 0.5 mm	Cross-process table	Protolabs Network
Snap-fit base thickness and hook depth; clip width	≥ 1 mm; ≥ 5 mm		Protolabs Network
Strain to failure across the layers	0.53–0.70 of XY (strength the same)	PA 12, PA 11, PP on the Jet Fusion 5200	HP
Expected tolerance	±0.3 %, floor ±0.3 mm	SLS and MJF	Protolabs Network

Where the MJF sources disagree

Thinnest wall: 0.3 to 2 mm. HP and Xometry 0.3 mm, but for short walls; Protolabs, Stratasys Direct and the Protolabs Network table 0.5 mm; Materialise 1 mm; JLC3DP 1–2 mm by size. And a ceiling: Stratasys Direct keeps walls at or under 3 mm, while Protolabs calls 2.5–12.7 mm ideal.
Clearance printed together: 0.5 or 0.7 mm, from HP itself. HP's accuracy chapter and Stratasys Direct say 0.5 mm at 1 mm thickness; HP's design page and Xometry say 0.7 mm; Materialise 0.5 mm. Assembled after printing: 0.4 mm (HP, Xometry) or 0.6 mm (Materialise).
Minimum detail: 0.1 mm (HP) against 0.5 mm (Protolabs, Stratasys Direct, Xometry).
Tolerance under 30 mm: ±0.2 to ±0.3 mm in XY, and Z is worse. HP's own Cpk 1.33 figures for PA 11 are ±0.30 XY and ±0.42 mm Z; Xometry Asia states ±0.2 mm and Stratasys Direct ±0.25 mm without an axis. At 80 mm, HP's Z tolerance (±1.18 mm) is 2.7 times its XY one [derived], so a tight fit belongs in the XY plane.
Stratasys Direct's conversions: 0.015 in is printed as 0.4 mm (it is 0.381 mm), and 0.010 in as both 0.4 and 0.3 mm (it is 0.254 mm). The YAML keeps the printed inch values.

6. Injection moulding

The sources here are resin makers (DuPont, Covestro), a moulder that publishes its tooling limits (Protolabs) and two online bureaus (Fictiv, and the Boothroyd Dewhurst checklist for screening). T below is the nominal wall.

Wall

Rule	Value	Applies when	Source
Recommended wall, by resin	ABS 1.14–3.56; PC 1.02–3.81; PP 0.89–3.81; nylon 0.76–2.92; acetal 0.76–3.05 mm	Protolabs' table, which it credits to manufacturingcenter.com	Protolabs
Wall that moulds stably	1.5–2.5 mm; small parts 1 mm, hand-sized 2 mm; sections near 3.8 mm start to sink	Thermoplastics in general	Protolabs
Thin-walled part	main walls under 1.5 mm need high-performance moulding		Covestro
Variation of the nominal wall	up to about 25 %	Low-shrinkage resins (most amorphous and filled grades)	Covestro
Critical thickness of polycarbonate	about 4.76 mm (3/16 in); thicker walls can fail brittle on impact	Medium-viscosity PC at room temperature; less when cold	Covestro

Draft

Rule	Value	Applies when	Source
Draft	0.5° vertical faces; 2° most situations; 3° shut-offs and light texture (PM-T1); 5° or more PM-T2		Protolabs
Draft	≥ 0.5°, 1° preferred; 3–5° for Apec high-heat PC and TPU	Covestro resins	Covestro
Draft	1–2° smooth; 3° light texture; 5° or more heavy texture		Fictiv
Draft, Table 3.01	Delrin 0–¼° under 25.4 mm deep (½° deeper); reinforced nylons ¼–½° (½–1° deeper)	DuPont resins, smooth finish	DuPont
Extra draft for texture	1° per 0.001 in of depth (DuPont); 1° plus 1° per 0.001 in (Covestro); 1.5° per 0.001 in (Fictiv)		DuPont; Covestro; Fictiv

Ribs and gussets

Rule	Value	Applies when	Source
Rib or gusset thickness	≤ 0.6 T	Avoids sink where the rib meets the wall	Protolabs; Boothroyd Dewhurst
Rib thickness	0.5–0.6 T		Fictiv
Rib base thickness (Table 2-1)	0.5 T for minimal sink (0.4 T on high gloss; filled grades 0.55–0.6 T); 0.66 T if slight sink is acceptable	Covestro PC, PC/ABS, PC/PET and TPU	Covestro
Rib thickness	0.4 T for appearance to 0.6 T for structure	Figure 4.07, read from the rendered figure (no text layer)	DuPont
Rib height	≤ 2.5 T	Several short ribs if taller	Fictiv
Rib height	≤ 3 × the rib base	Fill, venting and ejection	Covestro
Rib spacing; rib draft	≥ 2 T between short ribs; ≥ 0.5° per side		Covestro
Fillet at the rib base	0.5 × the rib (DuPont); 0.125 T (Covestro); 0.25–0.5 T but at most 0.254 mm (Fictiv)		DuPont; Covestro; Fictiv
Gusset thickness	0.5–0.67 T where sink matters		Covestro

Bosses and inserts

Rule	Value	Applies when	Source
Boss wall	0.4–0.6 × the wall it rises from	Add gussets rather than thicken	Protolabs
Boss wall	≤ 0.6 T		Fictiv
Boss wall	0.6 T under 3.175 mm walls, 0.4 T above	Figure 3.10, read from the rendered figure (no text layer)	DuPont
Boss outside diameter	2–2.5 × the hole (DuPont); 2.0–2.4 × the screw or insert (Covestro)		DuPont; Covestro
Boss draft	0.5–3°, by height; or mould solid and drill		Protolabs
Boss height	over 5 × its outside diameter is tall (thick base, sink)		Covestro
Pilot hole for a thread-cutting screw	0.88 × the screw's outside diameter	Polycarbonate	Covestro
Material under a moulded-in insert	≥ 1/6 of the insert diameter	Limits sink	DuPont

Corners, holes, gates and undercuts

Rule	Value	Applies when	Source
Inside corner radius	0.5 T (DuPont; Fictiv as a minimum); 0.15 T (Covestro); outside = inside + T (Fictiv, Covestro)		DuPont; Fictiv; Covestro
Smallest corner radius	0.508 mm (0.020 in)	Even where a sharp edge is wanted	DuPont
Blind cored hole depth	≤ 2 × D (DuPont); ≤ 3 × D, 5 × D only with symmetric slow filling (Covestro)	D the core pin	DuPont; Covestro
Core supported at both ends; floor under a blind hole	6 × D (up to 10 × D); ≥ D/6		Covestro; DuPont
Gate thickness	≥ 0.5 T unfilled; 2/3 T cosmetic parts; down to 1/3 T for filled polyamides; ≥ 0.8 T for walls under 1.5 mm		Covestro
Fan-gate land	≤ 1.524 mm (0.060 in)		Covestro
Strippable undercut	≤ 5 % of the diameter, bevelled (Delrin); 6–10 % (Zytel); 1 % glass-reinforced (2 % from a hot mould)		DuPont
Strippable undercut	≤ 2 % (Apec high-heat PC, filled grades); TPU about 5 %, up to 10 %; avoid in stiff PC and PC/ABS		Covestro
Tolerance	±0.08 mm machining, plus at least ±0.002 mm/mm for the resin	Protolabs aluminium tooling	Protolabs
Part depth from the parting line	≤ 101.6 mm (203.2 mm if the parting line runs through the middle)	Protolabs	Protolabs

Where the moulding sources disagree

Rib thickness: 0.4 T to 0.66 T. ≤ 0.6 T (Protolabs, Boothroyd Dewhurst), 0.5–0.6 T (Fictiv), 0.5 T for minimal sink or 0.66 T for slight sink (Covestro), 0.4–0.6 T (DuPont, from a figure). They agree once the cosmetic goal is stated: high gloss wants 0.4 T, hidden faces can take 0.66 T.
Rib height: 2.5 T against 3 × the rib. With a 0.5 T rib, Covestro's limit is 1.5 T, so Fictiv allows ribs 1.7 times taller [derived].
Fillet at the rib base. At T = 2.5 mm and a 1.25 mm rib: DuPont 0.63 mm, Covestro 0.31 mm, Fictiv 0.63–1.25 mm [derived]. Fictiv's own 0.254 mm cap is below its range for any wall over about 1 mm, and below DuPont's 0.508 mm smallest radius; it reads as a slip.
Inside corners: 0.5 T (DuPont, Fictiv) against 0.15 T (Covestro, which calls it a compromise between strength and appearance).
Texture draft at 0.05 mm depth: 2° to 3° [derived]: DuPont adds 2°, Covestro gives 3° in all, Fictiv adds 3°. Covestro counts its 1° base inside the rule; DuPont and Fictiv add to the smooth-face draft.
Blind hole depth: 2 × D (DuPont) against 3 × D (Covestro).
Standards. Tolerances for moulded parts are set by ISO 20457. Its 2018 edition was withdrawn on 2026-08-06 and replaced by ISO 20457:2026; DIN 16742 (which followed DIN 16901) is withdrawn. Both are paid and were not read; no rule here takes a value from them.

7. Sheet metal

Symbols: T thickness, R inside bend radius, K K-factor. The deep sheet-metal sweep, with more sources (OSH Cut, Fictiv, PEM, the CAD tools), is in #119; the rows here are the profile values, with the same source ids. A shop's own table beats all of them: SendCutSend publishes its tooling per stock size, and ten 5052 and mild-steel rows are in the YAML (shop_tables).

The same sheet-metal rule from different sources, evaluated at 1.5 mm thickness and radius, with one shop's real tooling

Bend radius and K-factor

Rule	Value	Applies when	Source
Minimum inside bend radius	R ≥ T	Generic	Protolabs Network; Greg Paulsen, Machine Design; Boothroyd Dewhurst
Minimum inside bend radius	R ≥ T; coining nearly 0; air bending 1–2T, set by the V-die	Mild steel 0.02–0.13 in; 3003 and 5052 about the same	Gerald Davis, The FABRICATOR
Minimum inside bend radius	4–8T	6061 and 2024; aluminium cracks most bending along the grain	Gerald Davis, The FABRICATOR
Standard radii; one radius for every bend	0.76, 1.52, 2.29, 3.05 mm (0.030–0.120 in)	Protolabs' 3-day tooling	Protolabs
K-factor	0.3–0.5 (average 0.4468); 3–5 test bends for a real value	Generic	Protolabs Network
K-factor, air bending, R ≤ T / T–3T / > 3T	soft 0.33 / 0.40 / 0.50; steel 0.38 / 0.43 / 0.50; stainless 0.40 / 0.45 / 0.50	Generic table (bottoming and coining rows in the guide)	Protolabs Network
K-factor	0.33–0.50, per SKU in the specs file	SendCutSend's tooling	SendCutSend, specs
Bend allowance	BA = π(R + K·T)·A/180, K from the inside face	Any CAD	SOLIDWORKS help

Flanges, holes and the bend

Rule	Value	Applies when	Source
Minimum flange	≥ 4T	Shorter: tool marks, a backup strip, or milling after	Protolabs; Gerald Davis, The FABRICATOR
Minimum flange	≥ 3.5 × (T + R)		Century Tywood
Minimum bend height	≥ 2T + R		Protolabs Network
Hole to bend	≥ 2T from the start of the bend radius	Davis: to the hole's edge	Protolabs Network; Gerald Davis, The FABRICATOR
Hole to bend	≥ 2T + R (datum not stated)	Screening question	Boothroyd Dewhurst
Hole to bend; slot to bend	≥ 2.5T + R; ≥ 4T + R	"From any bends"	Greg Paulsen, Machine Design
Punched hole to bend	≥ 1.5 × (T + R), inside face to hole edge		Century Tywood
Features at risk of distortion	within about 4T of a bend	Fix with relief cuts or a different radius	Protolabs
Minimum hole	≥ T	Punching (the punch breaks below it); lasers go smaller	Protolabs; Gerald Davis, The FABRICATOR
Hole to edge	1.574 mm for T ≤ 0.914 mm, else 3.175 mm	Inserts follow the hardware maker	Protolabs
Hole to edge	≥ 2T; ≥ T		Boothroyd Dewhurst; Protolabs Network
Hole to edge	1/16 in for T ≤ 1/32 in, else max(2T, 1/8 in)	Punched holes	Century Tywood
Hole spacing	≥ 2T; ≥ 6T		Protolabs Network; Greg Paulsen, Machine Design

Reliefs, hems and small features

Rule	Value	Applies when	Source
Bend relief depth	≥ T + R; cut with curves so cracks do not start		Gerald Davis, The FABRICATOR; Century Tywood
Bend relief depth and width	≥ T + R + 0.5 mm from the bend line; width ≥ T/2	CAD tools measure depth from different datums	SendCutSend
Bend relief width and length	width ≥ T, length > R		Greg Paulsen, Machine Design; width also Protolabs Network
Corner gap between flanges	≥ 0.4 mm (0.015 in)		SendCutSend
Hem: inside diameter; return	≥ T; ≥ 6T	Open and closed hems	Protolabs
Hem: inside diameter; return	≥ T; ≥ 4T (tear-drop opening ≥ T/4); avoid flat hems		Greg Paulsen, Machine Design
Tab width; notch width	≥ max(2T, 3.2 mm); ≥ max(T, 1.016 mm); both ≤ 5 × width long		Protolabs
Countersink to bend; to edge; to each other	≥ 3T; ≥ 4T; ≥ 8T		Greg Paulsen, Machine Design
Curl outside radius	≥ 2T		Greg Paulsen, Machine Design
Bend angle tolerance	±1°	Protolabs; SendCutSend up to 24 in, ±2° above, bends at most 120–130°	Protolabs; SendCutSend
Bend-to-hole tolerance	±0.38 mm under 0.13 in stock, ±0.635 mm above	Across 3+ bends ±0.76 / ±1.016 mm	Protolabs
Laser kerf	about 0.3 mm (waterjet 0.5–1 mm); split it between mating parts		Protolabs Network

Where the sheet-metal sources disagree

At T = R = 1.5 mm (the chart above) [derived]:

Minimum flange: 4.5 to 10.5 mm. 2T + R (Protolabs Network) gives 4.5 mm, 4T (Protolabs, Gerald Davis) 6 mm, 3.5 × (T + R) (Century Tywood) 10.5 mm. SendCutSend's real tooling for 1.5 mm mild steel needs 7.85 mm, longer than the 4T rule. Thin stock is worse: on 0.76 mm steel SendCutSend needs 7.26 mm, 9.5T [derived from shop_tables].
Hole to bend: 3 to 6 mm, on four different datums. 2T from the tangent (Protolabs Network, Davis), 2T + R with no datum (Boothroyd Dewhurst), 2.5T + R "from any bends" (Paulsen), 1.5 × (T + R) from the inside face to the hole edge (Century Tywood), and Protolabs' warning zone of 4T. A check must state its datum.
Relief width: T/2 (SendCutSend) against T (Protolabs Network, Paulsen). Depth agrees at about T + R, with SendCutSend adding 0.5 mm.
Hem return: 6T (Protolabs) against 4T (Paulsen).
R ≥ T is not a safe test either way. SendCutSend bends 5052 at 0.36–0.60T on stock up to 2.3 mm and at 1.0–1.34T from 2.5 mm up (eight thicknesses in its specs JSON; the four in shop_tables give 0.36–1.0T), and mild steel at 0.53–0.85T from 1.9 mm. Davis asks 4–8T for 6061 and 2024, and SendCutSend's file backs him: it publishes bend specs for no 6061 or 7075 stock, and bends its one 2024 sheet (0.64 mm) at R = 2.8T [all derived from bending_specs]. #118 already records this for the planned check S5.

8. CNC machining

D below is the tool or hole diameter. Two pages here are by named engineers at Xometry: Joel Schadegg and Greg Paulsen (10 tips) and Dean McClements and Aaron Lichtig (internal corner radii).

Corners, pockets and tool reach

Rule	Value	Applies when	Source
Inside vertical corner radius	≥ 1/3 of the cavity depth; about 1 mm over the tool radius cuts a better finish; a T-bone undercut if it must be sharp	Pockets	Protolabs Network
Inside corner radius	1.3 × the tool radius		Joel Schadegg and Greg Paulsen, Xometry
Inside corner radius	tool radius + 0.5–1.27 mm (0.02–0.05 in)	So the tool does not stop and pivot in the corner	Dean McClements and Aaron Lichtig, Xometry
Inside corner radius	≥ 0.8 mm where possible, a little over the tool		Fictiv
Floor radius	0, 0.5 or 1 mm (flat or bull-nose end mills); others with ball end mills		Protolabs Network
Cavity depth	≤ 4 × its width		Protolabs Network; Boothroyd Dewhurst
Cavity depth	≤ 3–5 × its width (the YAML keeps 3)		Joel Schadegg and Greg Paulsen, Xometry
Cavity depth that machines cheaply	2–3 × D; 4 × D and deeper costs more		Protolabs Network
End-mill depth of cut	≤ 15 × D plastics, 10 × D aluminium, 5 × D steel		Fictiv
Deep cavity; deepest with special tools	from 6 × D; up to 30 × D		Protolabs Network
End-mill cutting length	3–4 × D standard		Protolabs Network
Length of cut, long-reach miniature end mills	3 × D standard flute; ≥ 5 × D long flute	A tool maker's catalogue, for comparison	Harvey Tool
Deepest milled feature from each side	≤ 50.8 mm (2 in)	Protolabs	Protolabs

Walls and small features

Rule	Value	Applies when	Source
Minimum wall, metal / plastic	0.8 / 1.5 mm (0.5 / 1.0 mm feasible case by case)	Plastics warp and soften	Protolabs Network
Minimum wall, metal / plastic	0.794 / 1.5 mm		Joel Schadegg and Greg Paulsen, Xometry
Minimum wall, metal / plastic	0.25 / 0.5 mm	Milled	Fictiv
Feature thickness; nominal part thickness	> 0.51 mm; > 1.02 mm	Milling	Protolabs
Turned wall; smallest turned diameter	≥ 0.51 mm; ≥ 0.76 mm (points steeper than 30°)	Turning	Protolabs
Slender feature	height ≤ 4 × width		Protolabs Network
Smallest tool or cavity	2.5 mm on most machines; 0.05 mm with micro-machining tools (printed beside 0.005 in, which is 0.127 mm)		Protolabs Network; Joel Schadegg and Greg Paulsen, Xometry
Engraved text stroke	≥ 0.457 mm, 0.3 mm deep	Plastics and soft metals	Protolabs

Holes and threads

Rule	Value	Applies when	Source
Hole	≥ 1 mm; standard drill sizes		Protolabs Network
Hole depth	≤ 4 × D; 10 × D typical, 40 × D with special drills		Protolabs Network
Hole depth	≤ 4 × D; up to 10 × D at extra cost		Joel Schadegg and Greg Paulsen, Xometry
Drilling depth; blind hole	≤ 12 × D; drill 25 % deeper than the depth needed		Fictiv
Turned holes	≥ 1 mm on the axis; radial 2 mm (1 mm in aluminium and brass)		Protolabs
Thread length	1.5–3 × D, 3 × D recommended		Protolabs Network
Thread length	≤ 2 × D		Joel Schadegg and Greg Paulsen, Xometry
Thread engagement	1–1.5 × D; a tap deeper than 3 × D is deep		Fictiv
Unthreaded length at the bottom of a blind hole	1.5 × D for tapped threads (below M6)		Protolabs Network
Unthreaded length at the bottom of a blind hole	≥ 0.5 × D		Joel Schadegg and Greg Paulsen, Xometry
Thread size	M6 or larger recommended (M1 possible)		Protolabs Network
Thread range	M2–M12 (UNC and UNF #2 to 1/2 in); do not model internal threads	Protolabs' automated factory	Protolabs
Clearance round an internal undercut	≥ 4 × the undercut depth to the next wall	T-slot cutters 3–40 mm wide	Protolabs Network

Tolerances

Rule	Value	Applies when	Source
General tolerance	±0.1 mm typical; ±0.02 mm feasible		Protolabs Network
Default tolerance	±0.125 mm or better	When none is given	Protolabs Network
Machining tolerance	±0.13 mm (±0.005 in), otherwise ISO 2768-1 medium or fine	Protolabs' automated milling	Protolabs
Tolerance the shop may loosen	tighter than ±0.05 mm		Fictiv

Where the CNC sources disagree

Inside corner radius: the rules agree. For a 12 mm deep pocket cut with a 6 mm end mill [derived]: depth/3 gives 4 mm (Protolabs Network), 1.3 × the tool radius 3.9 mm (Schadegg and Paulsen), tool radius + 0.02–0.05 in 3.5–4.3 mm (McClements and Lichtig). Fictiv's 0.8 mm is a floor, not a target.
Minimum wall in metal: 0.25 to 0.8 mm. Fictiv 0.25 mm; Xometry 0.794 mm; Protolabs Network 0.8 mm (0.5 mm feasible). In plastic: 0.5 mm (Fictiv) to 1.5 mm (Protolabs Network, Xometry). The chart at the top shows them.
Hole depth: 4 × D (Protolabs Network, Xometry) against 12 × D (Fictiv); Protolabs Network calls 10 × D typical and 40 × D feasible, so 4 × D is "cheap", not "possible".
Thread length: 3 × D recommended (Protolabs Network) against at most 2 × D (Xometry) and 1–1.5 × D of engagement (Fictiv). The run-out at the bottom of a tapped blind hole is 1.5 × D (Protolabs Network) or 0.5 × D (Xometry).
Protolabs Network against itself: holes are feasible above 1 mm in one row and features down to 0.05 mm with micro tools in another. That 0.05 mm is printed beside 0.005 in, which is 0.127 mm, so one of the two is a slip; the YAML keeps the mm value and says so.
Standards. Protolabs names ISO 2768-1 (general tolerances) as its default. It is paid and was not read.

9. What this changes in cad-agent

cadagent.process (#99) can load process-profiles.yaml as it stands: rules by process and feature, the evaluator in tools/process_profile_figures.py, and the SendCutSend shop table. The acceptance in #99 (FDM PETG, PLA, ASA, PA-CF and sheet-metal 5052 and mild-steel profiles) needs the material rows from compliant-mechanisms §5 joined to the FDM rules here, and the shop table for sheet metal.
Planned sheet-metal checks S1–S8 (research/fea-and-process-tools.md §5): every check should name its datum and its source, and read a shop table first. See #118's comment on S1 and S5.
Pitfall checks (#97) can cite a rule id from the YAML in their report rows, which gives the credit by name.

10. Sources

People and organisations whose published rules this page uses. Each entry in the YAML says what was read and when.

3D printing

Protolabs Network (formerly Hubs): How to design parts for FDM 3D printing; 3D printing geometry limitations; Dimensional accuracy in 3D printing; Threads and screws for 3D printing; Snap-fit joints for 3D printing; How to design parts for SLA 3D printing; How to design parts for SLS 3D printing.
Prusa Research, Prusa Knowledge Base: Modeling with 3D printing in mind; Elephant foot compensation; Hollowing.
Xometry Europe: FDM 3D Printing Design Tips (the page quotes Nikolaus Mroncz, Head of Sales Engineering).
Niko Mroncz, Xometry Asia: SLA 3D Printing Design Guidelines: 8 Essential Tips (2025); 8 Essential Design Tips for SLS 3D Printing (2025). Xometry Asia: HP MJF design guidelines (2020). Xometry: MJF service; SLS service.
Joel Schadegg (written by) and Aaron Lichtig (updated by), Xometry: FDM Mini-Guide.
Stefan Hermann, CNC Kitchen: Tips & Tricks for Heat-Set Inserts (2021); Are Our Heat-Set Insert Datasheets Wrong? (2026).
Christoph Klahn, Daniel Singer, Mirko Meboldt: Design Guidelines for Additive Manufactured Snap-Fit Joints, Procedia CIRP 50 (2016).
Formlabs: Form 4 Design Guide; the technology behind Form 4; design specifications for Form 3/3B and Form 2; How to hollow out 3D models; Fuse Series SLS Design Guide (2023).
HP: Jet Fusion 5200 mechanical properties, 4AA7-7084ENW (2020); MJF Handbook, Design for accuracy (2019); How to design a 3D print model for MJF; Designing 3D printed joints; Jet Fusion 5200 dimensional capability, 4AA7-7166ENW (2020).
Protolabs: SLA design guidelines; SLS design guidelines; MJF design guidelines; Nylon 3D printing tips; Multi Jet Fusion for functional parts.
Materialise: design guidelines for Taurus (SLA), PA 12 (SLS) and PA 12 (MJF).
Stratasys Direct: Multi Jet Fusion design guide (2019).
Franz-Josef Kerl, EOS: Design Rules Overview LS (2011).
JLC3DP: 3D printing design guidelines.
ELEGOO: Hollowing and holes in ELEGOO SatelLite (2026).
Mango3D (Lychee Slicer): Voxels hollowing (2026).

Injection moulding

Protolabs: Injection molding design guidelines; Ribs, gussets and materials; Plastic boss design.
DuPont: General Design Principles, Module I (2000; a distributor's copy).
Covestro: Part and Mold Design, a design guide (2015).
Fictiv: Injection molding design guide (2025).

CNC machining

Protolabs Network (formerly Hubs): How to design parts for CNC machining; 14 tips to reduce the cost of CNC machining.
Protolabs: CNC milling and CNC turning design guidelines.
Fictiv: CNC machining design guide (2021).
Joel Schadegg (written by) and Greg Paulsen (updated by), Xometry: 10 tips to improve your CAD designs for CNC machining (2022).
Dean McClements (written by) and Aaron Lichtig (updated by), Xometry: Optimizing internal corner radii (2020).
Harvey Tool: long-reach miniature end mills.

Sheet metal

Protolabs: Design Guidelines for Sheet Metal Fabrication.
Protolabs Network (formerly Hubs): Sheet metal fabrication design guide.
Greg Paulsen (then Director of Applications Engineering, Xometry): Tips for Making Sheet-Metal Parts, Machine Design (2017).
Gerald Davis: Design tips for sheet metal, The FABRICATOR (2001).
Century Tywood: Manufacturing Reference for Sheet Metal Products.
Boothroyd Dewhurst, Inc.: DFM Design Review Checklist (also used for moulding and CNC).
SendCutSend: Bend reliefs and corner reliefs (2024); ordering guide; engineering specs JSON.
Dassault Systèmes: SOLIDWORKS help, K-Factor.

Standards (paid; cited by number and title only, not read, and no rule takes a value from them; listed in the YAML under standards)

ISO 2768-1:1989 General tolerances, Part 1: linear and angular dimensions.
ISO 20457:2026 Plastics moulded parts: tolerances and acceptance conditions (the 2018 edition is withdrawn); DIN 16742:2013, the same title, withdrawn.
ISO/ASTM 52910:2018 Additive manufacturing, design: requirements, guidelines and recommendations (its abstract says it gives no process- or material-specific data).
ISO/ASTM 52911-2 Additive manufacturing, design, Part 2: laser-based powder bed fusion of polymers.

11. Not verified, and next

The Protolabs Network design-rules poster that compares every printing process is an image in perspective; it was not read, and none of its numbers are used.
Xometry's FDM quick design guide (a 10 mm bridge, among others) returned HTTP 403 to every fetch and has no archive copy; not used. Xometry's US MJF guide is an e-mail-gated e-book, and its European MJF pages returned 403.
HP's MJF Handbook chapters other than "Design for accuracy" (best practices, design for cleaning, tolerancing, hinges) sit behind a sign-up form; HP's own escape-hole size was not found.
EOS's gap-against-wall chart is an image; its row is marked (u). DuPont's rib and boss proportions (Figures 4.07 and 3.10) have no text layer either, so they were read from the rendered figures and are marked read.
VDI 3405 Blatt 3 (design rules for laser sintering and melting) could not be opened; it is not cited.
Next, filed as issues: a cadagent.process loader with one check that reads this file, and re-reading the (u) row from EOS's chart.