Wall thickness in 3d printing: what is the rule?

At least 1.2 mm for FDM and about 0.8–1 mm for SLA and SLS; walls should be at least two nozzle widths. Thinner walls fail to print or break.

Overhangs in 3d printing: what is the rule?

Keep overhangs to about 45° or less in FDM, or plan supports. Steeper overhangs droop without support and leave rough surfaces.

Holes and fits in 3d printing: what is the rule?

Add about 0.2–0.4 mm clearance to holes and mating parts. Printed holes shrink and layers add roughness.

Orientation in 3d printing: what is the rule?

Print so the main load is along the layers, not across them. Parts are weakest between layers.

Heat in 3d printing: what is the rule?

Do not use PLA for parts that see heat above about 60 °C; use PETG, ABS, nylon or a metal part. PLA deforms in a hot car or near a heater.

3D printing: design rules

Building parts layer by layer (FDM, SLA/resin, SLS powder, metal powder bed) for prototypes and complex shapes.

Typical tolerance

Typical: FDM ±0.2–0.5 mm, SLA and SLS about ±0.1–0.3 mm. Printed holes come out slightly small.

Files to send

STL or 3MF for printing; STEP if the shop should check geometry first.

Common materials

PLA, PETG, ABS, nylon, resin, SLS nylon, aluminium and stainless steel (metal printing). PLA softens at about 60 °C.

The rules, with reasons

Wall thickness. At least 1.2 mm for FDM and about 0.8–1 mm for SLA and SLS; walls should be at least two nozzle widths. Why: Thinner walls fail to print or break.
Overhangs. Keep overhangs to about 45° or less in FDM, or plan supports. Why: Steeper overhangs droop without support and leave rough surfaces.
Holes and fits. Add about 0.2–0.4 mm clearance to holes and mating parts. Why: Printed holes shrink and layers add roughness.
Orientation. Print so the main load is along the layers, not across them. Why: Parts are weakest between layers.
Heat. Do not use PLA for parts that see heat above about 60 °C; use PETG, ABS, nylon or a metal part. Why: PLA deforms in a hot car or near a heater.

Before you ask for a quote

Technology and material
Quantity
STL or 3MF in millimetres
Surface finish needs
Temperature and load of the use

Common mistakes

Wrong units in the file
Zero clearance on mating parts
PLA in a hot environment
Walls thinner than two nozzle widths

Agents and scripts can check a design automatically with the check_design MCP tool or POST /api/design-rules. How to connect.

Request a quote Find manufacturers

Typical rules of thumb, not a guarantee. The manufacturer's own design guidelines override them: ask for them and check your design against both before ordering.