Resources
Design guidelines for additive manufacturing
Practical rules of thumb we use every day to help engineers, designers and buyers prepare parts that manufacture cleanly the first time. Updated as we learn.
Quick answer
Designing for additive is different from designing for machining or moulding. Wall thickness, layer orientation, minimum feature sizes and material behaviour drive whether a part comes out right the first time. These guides cover the essentials — tolerances, walls, holes, files, finishes and material picks — for FDM, SLA, SLS, MJF and metal processes.
Guides
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Concise references you can use when preparing a new part or reviewing a design.
Tolerances by process
What dimensional accuracy to expect from each 3D printing process, and when to plan for post-machining.
- •FDM: ±0.5% or ±0.5 mm (whichever greater)
- •SLA: ±0.2% or ±0.1 mm — highest polymer accuracy
- •SLS/MJF PA12: ±0.3% or ±0.3 mm typical
- •Metal SLM: ±0.2 mm as-printed, ±0.05 mm post-machined
Wall thickness minimums
How thin walls can go without warping, cracking or failing during printing.
- •FDM: 0.8-1.2 mm minimum (2× nozzle)
- •SLA: 0.5 mm for supported walls, 1 mm free-standing
- •SLS/MJF: 0.8 mm minimum, 1.5 mm structural
- •Metal SLM: 0.4 mm supported, 0.8 mm free-standing
Features: holes, threads, snaps
Minimum feature sizes for holes, threaded inserts, snap fits and living hinges.
- •Holes: min 1 mm, oversize by 0.2 mm for post-drill fit
- •Threads: use inserts for durability — Heat-set for FDM, brass for SLS/MJF
- •Living hinges: PP or ULTEM 1010 — layer orientation critical
- •Snap fits: PA12 (SLS/MJF) is the go-to for repeated flex
File preparation
Best-practice for exporting CAD to files that manufacture cleanly.
- •STEP (.stp) preferred — carries units and tolerance
- •STL: use fine tessellation (chord height 0.01 mm)
- •Verify watertight geometry before upload
- •Include a README with material, quantity, finish, deadline
Finishes & post-processing
Options for making 3D-printed parts look and feel production-ready.
- •As-printed: fastest, layer lines visible on FDM
- •Bead blasting: uniform matte on SLS, MJF, metal
- •Vapor smoothing: glossy on ABS, ASA (chemical process)
- •Dyeing: black or coloured for nylon SLS/MJF parts
- •Paint + primer: any process, best on sanded surfaces
Material selection cheat sheet
Quick guidance on picking the right material for common part requirements.
- •Cost + speed: PLA (FDM), PA12 (MJF)
- •Impact resistance: PC, PA12, ABS-ESD
- •Heat > 100°C: ULTEM 9085, PEEK, PA12-CF, metal
- •Chemical resistance: PA12, PP, PEEK, ULTEM
- •Flexible / rubbery: TPU 95A (SLS), elastic resin (SLA)
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