Surface guide
QR codes on 3d-printed qr codes
A printed-in-relief QR code relies on shadow for contrast, which makes it lighting-dependent and unreliable. Two-colour printing with a filament change is far better: real luminance contrast, and it works in any light.
| Typical scan distance | 20–50 cm |
|---|---|
| Minimum code width | 4–8 cm |
| Error correction | H |
Relief alone is unreliable
A raised or recessed pattern in one colour has no luminance contrast — only shadow. Rotate the object, or move the light, and the contrast inverts or vanishes. Codes like this scan on a desk under a lamp and fail everywhere else.
Two-colour is the fix
Print the base in a light filament, pause at the layer where the code begins, swap to a dark filament, and continue. The result has genuine colour contrast and scans like paper.
Most slicers support a filament change at a layer (M600 in Marlin). A single-nozzle printer
handles this fine — no multi-material hardware needed.
Geometry
- Modules at 1.5 mm or larger, and ideally a multiple of your nozzle width (0.4 mm nozzle → 1.6 mm modules = 4 extrusion widths).
- Two to three layers of colour depth is plenty; more just wastes filament.
- Recess the dark modules rather than raising them if printing in relief — recessed modules hold shadow more consistently than raised ones.
- Print the code on the top surface, not a vertical wall, so layer lines run across the modules rather than along them.
If you must use single-colour relief
Use error correction H, make modules at least 2 mm, and recess to 0.6 mm or more. Accept that it will need directional lighting.