Should I add chamfers or fillets?

Yes — both improve strength and printability. Chamfered bottom edges print cleaner; filleted internal corners are much stronger.

Can I print moving parts in one go?

Yes — 'print-in-place' hinges and joints work well with FDM and SLS. Leave 0.3–0.5 mm clearance between moving surfaces.

Does my maker handle slicing settings?

Yes — you supply the geometry and intent; they pick layer height, infill, supports and orientation to suit.

Designing Parts for 3D Printing

Design rules for 3D printing — wall thickness, overhangs, supports, tolerances and orientation for FDM, resin and SLS.

3D printing is the most forgiving manufacturing process there is — but it still has rules. Following a handful of design guidelines will dramatically improve how your parts print, look and perform. This guide covers the essentials for FDM, resin and SLS.

Wall thickness

FDM (filament printing): minimum wall thickness around 0.8 mm (two nozzle widths). For anything load-bearing aim for 1.6–2.4 mm. Very thin walls print but warp easily.

Resin (SLA/MSLA): minimum 0.5 mm for unsupported walls, 0.8 mm for supported. Resin is brittle, so thin walls snap.

SLS nylon: 0.7 mm minimum, but 1.0 mm gives much more consistent results.

Overhangs and supports

FDM: overhangs steeper than 45° from vertical usually need support material. Bridges up to about 20 mm print cleanly unsupported; longer bridges sag.

Resin: needs supports for almost every overhang and unsupported island. Your maker handles support generation — but design so heavy features are well-supported.

SLS: no supports needed — the unfused powder supports the part. This is why SLS is so good for organic and complex geometry.

Holes and threads

Holes shrink slightly during printing. For a press-fit, design holes at nominal size; for a clearance fit, add 0.2–0.4 mm to the diameter.

Threads: small M3/M4 threads can print directly but wear quickly. For anything that will be screwed and unscrewed repeatedly, design for a heat-set brass insert — they're the standard.

Tolerances and fit

FDM tolerance is typically ±0.2 mm. For two parts that snap together, leave 0.3 mm clearance. For sliding fits, 0.4–0.5 mm. SLS holds ±0.3 mm but with much more isotropic behaviour. Resin holds ±0.1 mm but can shrink up to 1% on large parts.

Orientation matters

FDM parts are weakest between layers. Orient the part so loads run along the layers, not across them. A bracket that hooks vertically should be printed standing up so the hook isn't snapping along a layer line.

Surface finish is best on the top and outside faces; the build-plate side is usually flattest but featureless. Tell your maker which surfaces matter visually.

Hollowing and infill

FDM parts are partially hollow inside (typically 15–30% infill). For load-bearing parts, request higher infill (50–80%) or solid walls. For resin and SLS, parts are usually solid unless you hollow them yourself to save material.

Small detail

FDM resolves about 0.4 mm minimum detail (single nozzle width). Resin resolves 0.1 mm easily. SLS resolves around 0.3 mm. If your part has fine text, logos or detail under 0.5 mm, resin is usually the right process.