Design Tips for 3D Printing

Designing for Manufacturability

3D printing gives you enormous design freedom, but it's not without constraints. Parts designed for CNC machining or injection molding often need modifications to print successfully. These guidelines will help you avoid common pitfalls and get better results on the first print.

Wall Thickness Guidelines

Wall thickness is one of the most common sources of print failures. Too thin and the wall won't print; too thick and you waste material and increase print time.

• FDM minimum wall: 0.8mm (2x nozzle diameter for 0.4mm nozzle)
• FDM recommended wall: 1.2mm-2.0mm for structural parts
• SLA minimum wall: 0.4mm for supported walls, 0.6mm for unsupported
• SLA recommended wall: 1.0mm+ for handling durability
• Keep wall thickness uniform when possible to avoid warping
• Gradual thickness transitions are better than abrupt changes

Overhangs and Support Structures

Both FDM and SLA can print overhangs, but there are limits. Understanding these limits helps you design parts that need less support, which means less post-processing and better surface quality.

• FDM can print overhangs up to 45° without support
• Bridges (horizontal spans) work up to about 10mm on FDM without support
• SLA handles overhangs better due to resin surface tension, but still needs supports for islands
• Design chamfers instead of 90° overhangs where possible
• Fillets at the base of vertical features reduce the need for support
• Self-supporting angles (>45° from horizontal) eliminate support entirely

Print Orientation Matters

How you orient your part on the build plate significantly affects strength, surface finish, support requirements, and print time. Layer lines create anisotropic properties: parts are weaker across layers than along them.

• Orient parts so load is applied along layers, not across them
• Place the best surface face-up (FDM) or away from supports (SLA)
• Minimize support contact with cosmetic surfaces
• Tall, thin features should be printed vertically for stability
• Round holes print best when their axis is vertical
• Consider splitting large parts and assembling them for optimal orientation per section

Tolerances and Fit for Assemblies

When designing parts that fit together, account for the printer's tolerance and material shrinkage. Press-fit and snap-fit dimensions need specific clearances.

• Clearance fit (loose): add 0.4mm gap per side (0.8mm total diameter difference)
• Transition fit (snug): add 0.2mm gap per side
• Press fit: add 0.1mm gap per side (test on your specific printer)
• Holes tend to print slightly undersized; add 0.1-0.2mm to hole diameters
• Test critical fits with a small test coupon before printing the full part
• SLA parts shrink slightly during post-cure; account for 0.1-0.3% shrinkage

File Preparation and Mesh Quality

A clean, watertight STL or 3MF file is essential for a successful print. Mesh errors can cause slicing artifacts, missing surfaces, or failed prints entirely.

• Export STL at sufficient resolution (0.01mm chord deviation or finer)
• Ensure your mesh is watertight (no holes, non-manifold edges, or flipped normals)
• Use mesh repair tools: Meshmixer, Netfabb, or 3D Builder (Windows)
• 3MF format is preferred over STL: it stores units, color, and is more compact
• Check for intersecting bodies and combine them with boolean operations before export
• Minimum feature size: 0.4mm for FDM, 0.15mm for SLA

Common Mistakes to Avoid

These are the most frequent issues we see from customers submitting parts for quoting. Avoiding them will save you time and revisions.

• Walls too thin: leads to gaps, weak spots, or unprintable geometry
• No draft on vertical text/logos: letters under 0.5mm wide won't print legibly
• Sharp internal corners: add fillets (R0.5mm+) to reduce stress concentration
• Unsupported flat ceilings: design arches or slopes instead of flat horizontal spans
• Ignoring orientation: parts designed without considering print direction often fail
• Over-engineering: 100% infill is rarely needed. 20-40% handles most loads
• Forgetting tolerances: parts designed to exact nominal dimensions won't fit together
• Huge flat bases: add a chamfer or fillet to the base edge to prevent warping/elephant's foot