How to Design for 3D Printing

Walls and minimum features

Keep walls at least ~1.2 mm for FDM and ~0.8–1.0 mm for SLS nylon. SLA can resolve finer detail, but thin unsupported walls still warp or crack in post-processing. Embossed text and logos need enough height (often 0.4–0.8 mm) and stroke width to survive the chosen layer height. Prefer fillets on internal corners — sharp re-entrant corners concentrate stress and are common crack starters on printed plastics.

Overhangs, bridges, and supports

FDM prefers overhangs under ~45° from vertical; steeper faces usually need supports that leave marks and add cost. Short bridges can work without supports if the gap is modest and the slicer can cool the strand. SLA and SLS handle complex undercuts better, but orientation still controls cosmetics, strength, and (for SLA) where support tips land on show surfaces. When you can, design self-supporting angles, chamfers, and gradual transitions instead of relying on heavy support trees.

Orientation and strength

Printed parts are often strongest in the plane of the layers and weaker across them. Align load paths with the layers when possible — for example, put bolt bosses so the clamp force isn’t trying to peel layers apart. Flat orientations can improve dimensional accuracy on critical faces; tall orientations may reduce bed footprint but increase the chance of layer delamination. For cosmetic faces, orient so support scars land on hidden sides.

Assemblies and clearances

Leave 0.3–0.5 mm clearance for mating printed parts unless you’ve already tested a tighter fit on the same process and material. Press-fits and snap-fits need intentional interference and flexible geometry — don’t assume molded tolerances. For SLS moving assemblies printed in place, plan powder removal paths and escape holes so sintered powder doesn’t lock the joint. Label holes and bosses clearly in CAD so you can verify them after the first print.

Hollowing, holes, and drains

Large solid blocks waste material and money. Hollow thick sections and add at least two escape holes (often 2–3 mm+) so resin or powder can leave the cavity. Keep internal ribs for stiffness instead of filling the whole volume. On FDM, use infill percentage as your “hollow vs solid” control rather than modeling every lattice by hand unless you need a specific pattern.

Validate with an instant quote

Export a clean STL or 3MF (watertight mesh, sensible units in millimeters), upload it, and confirm size limits before you wait on tooling. If any dimension exceeds the material’s max build size, we’ll flag a manual quote path. Iterate the CAD, re-upload, and compare prices — that’s usually faster than guessing wall thickness in a vacuum.