Design guide
Wall thickness
The single most common reason a part fails to print or breaks in service. Get this right and the rest of the design is much more forgiving.
Supported vs unsupported walls
FDM walls are built from extruded lines of plastic, typically 0.42 mm wide on a 0.4 mm nozzle. How thin you can go depends on whether the wall is braced on more than one side, or standing on its own like a fin.
Connected to other structures on at least two sides. Safe down to 0.8 mm (2 perimeters).
Freestanding fins or ribs need more meat — 1.0 mm minimum, or they wobble as the nozzle passes.
Aim for walls that are an integer multiple of the line width. The sweet spot for functional parts is 1.6 mm (4 lines): strong enough for most load paths, fast to print, clean to finish.
Recommended values per material
These are working numbers for our Bambu printers at 0.2 mm layer height. Thicker walls are always fine; thinner walls are a gamble.
| Material | Minimum (mm) | Recommended (mm) | Notes |
|---|---|---|---|
| PLA | 0.8 | 1.6 | — |
| PETG | 1 | 1.6 | — |
| ABS | 1 | 2 | Thinner walls cup as the part cools. |
| ASA | 1 | 2 | — |
| PA-CF | 1.2 | 2 | Fibre length sets the floor, go thicker on load paths. |
| TPU | 1.2 | 2 | Soft material, thin walls collapse under their own weight. |
Measured for a 0.4 mm nozzle. Larger nozzles raise the minimum proportionally.
Embossed & engraved details
Logos, serial numbers and feature labels need enough relief to survive the first layer pass. Embossed (raised) features must stand at least one layer proud; engraved (recessed) grooves must be wide enough for the nozzle to fit into.
| Material | Min stroke width (mm) | Min depth / height (mm) |
|---|---|---|
| PLA | 0.6 | 0.4 |
| PETG | 0.6 | 0.4 |
| ABS | 0.8 | 0.4 |
| ASA | 0.8 | 0.4 |
| PA-CF | 0.8 | 0.5 |
| TPU | 1 | 0.6 |
Text below these numbers either blurs together (engrave) or fails to deposit (emboss).
For best legibility, model text as recessed on a top surface and embossed on a side surface. Top-face embossing fights the z-seam and rarely looks crisp on FDM.
Minimum freestanding features
Standoffs, locating nubs, alignment teeth — anything sticking up from a surface needs enough cross-section that the nozzle doesn't knock it off in passing.
Treat 2 mm as the floor for any standalone protrusion. Below that, redesign the feature as a recess, a pin pressed in after the fact, or a cluster of smaller features that brace each other.
Common pitfalls
- Knife-edge walls where two surfaces taper to a point. The tip becomes a single bead and breaks off. Add a 0.8 mm flat at the edge.
- Internal ribs thinner than the outer wall — print speed jumps around as the slicer switches modes, leaving visible scars. Match rib thickness to the outer wall.
- Cosmetic text under 6 pt at 1× scale: layer lines blur the letterforms. Use a geometric sans (Inter, DIN) at 8 pt minimum.
Send it as a STEP if you can
STEP preserves true CAD geometry, so we can re-thicken walls before slicing if they're borderline. STL mesh is a one-way trip — once it's a triangle soup, we can only flag the issue and ask you to re-export.
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Last reviewed May 2026 · Rigid Prints engineering team