Why split into multiple parts?
Part exceeds maximum build size
Different sections need different materials or technologies
Easier printing (avoiding complex supports)
Easier post-processing or painting
Moving assemblies (hinges, sliders, gears)
Clearance guidelines
For parts that need to fit together after printing:
Press fit (holds without glue), per side:
FDM: 0.1–0.15mm
SLA: 0–0.05mm
Industrial SLA: 0–0.05mm
MJF: 0–0.1mm
Slip fit (goes together by hand and stays put, glued joints), per side:
FDM: 0.2–0.3mm
SLA: 0.125–0.2mm
Industrial SLA: 0.125–0.2mm
MJF: 0.2–0.3mm
Moving joints (hinges, sliders), per side:
FDM: 0.3–0.4mm
SLA: 0.2–0.3mm
Industrial SLA: 0.2–0.3mm
MJF: 0.3–0.4mm
FGF and TPU are in the full clearance table.
Alignment features
Always include alignment features so parts go together correctly:
Dowel pins and holes — Most reliable. Make the hole larger than the pin by twice the slip-fit clearance (0.4–0.6mm on FDM and MJF, 0.25–0.4mm on SLA).
Tongue and groove — Good for flat joints. Groove width = tongue width + clearance.
Keyed features — Asymmetric shapes that only fit one way. Prevents assembly errors.
Registration marks — Numbers or arrows on each piece for assembly sequence.
Bonding methods
Cyanoacrylate (super glue) — Fast, strong, works on all materials
Epoxy — Strongest bond, gap-filling, longer work time
Solvent welding — ABS + acetone, creates a chemical bond
Mechanical fasteners — Screws, bolts, heat-set inserts for removable connections
Friction/press fit — Use the press-fit clearance above; printed holes run slightly small, so it ends up a light press
Print-in-place assemblies
MJF can print moving assemblies (hinges, ball joints, chains) in a single print because the powder supports the part during printing. Design with at least 0.5mm clearance between moving surfaces, and more on long or enclosed channels so loose powder can get out.
FDM can print moving parts in place only where no support is needed between them, with 0.4–0.5mm clearance. SLA generally cannot print-in-place, because support material and trapped resin end up between the moving parts.
Tips
Always order a test assembly before committing to a production run
Provide assembly drawings or instructions with your order
Specify which dimensions are critical for fit
Send us your assembly files and we’ll review for printability.
Makelab is a professional 3D printing service in Brooklyn, NYC. Our engineers review every file for printability and can help optimize your design. Get an instant quote.
Learn more on our website:
Full Design Guidelines — comprehensive rules by technology
File Requirements — formats, mesh settings, export tips
Browse Materials — find the right material for your application