Design for 3D Printing: Best Practices

Universal Design Rules

Regardless of technology, three principles apply to every 3D printed part. First, maintain minimum wall thickness: 1.2 mm for FDM, 0.8 mm for SLS, and 0.5 mm for mSLA. Walls thinner than these minimums risk print failures, warping, or breakage during handling. Second, design for the tolerance of your chosen technology: ±0.15 mm for FDM, ±0.10 mm for SLS, ±0.05 mm for mSLA. Interference fits and snap-fit joints should account for these tolerances.

Third, always export your files as STL or STEP with sufficient mesh resolution. For mSLA parts with fine detail, use a chord deviation of 0.01 mm or finer. For FDM parts, 0.05 mm is adequate. Oversimplified meshes produce faceted surfaces; over-refined meshes create unnecessarily large files. Most CAD packages allow you to preview the mesh quality before export.

FDM-Specific Design Tips

FDM prints from the bottom up with support structures for overhangs beyond ~45 degrees. Design parts to minimize overhangs: use chamfers instead of fillets on bottom edges, orient the part so critical surfaces face upward, and avoid horizontal bridges longer than 10 mm without support. Internal channels should have teardrop cross-sections (pointed at the top) to self-support during printing.

FDM parts are weakest between layers (Z-axis). If your part must bear load in one direction, orient the print so that direction aligns with the X/Y plane. For threaded holes, design undersized pilot holes and tap them after printing, or use heat-set threaded inserts for reliable, repeatable fastening. Layer heights of 0.10 mm give the best surface finish; 0.20-0.30 mm are faster for internal or non-visible parts.

SLS and mSLA Design Tips

SLS requires no supports, making it ideal for complex geometries. However, trapped powder is a real concern: include escape holes (minimum 3 mm diameter) in hollow parts so unsintered powder can be removed. Thin walls down to 0.8 mm are possible, but walls under 1.0 mm over large spans may warp during cooling. The powder bed must cool slowly (12-24 hours), so design parts that fit within the 220 × 220 × 330 mm build volume to maximize batch efficiency.

mSLA design revolves around support placement. Every overhanging surface needs support, and support contact points leave small marks that require post-processing. Minimize downward-facing flat surfaces and orient critical surfaces away from the build plate. For hollow resin parts, include drain holes (minimum 2 mm) to let uncured resin escape. Thin walls can go as fine as 0.5 mm in resin, enabling delicate features impossible in other technologies.

Frequently Asked Questions