3D printable QR code generator

3D printing a QR code: what is worth knowing

Why 3MF and not STL

An STL file stores only shape: triangles and nothing else. When you open it in your slicer, everything arrives in a single colour and you have to separate by hand which part goes with which filament. 3MF is the format Bambu Studio, PrusaSlicer, Orca Slicer and Cura all use today, and it stores colour inside the file. That is why the main download here produces a 3MF holding two separate objects — the base and the raised code — each with the colour you picked on this page. When you open it, the slicer already knows what goes in each extruder.

If your printer is older or your slicer only accepts STL, there is the secondary download: a ZIP with the two parts as STL files and a note explaining how to place them in the same spot and assign a material to each.

Contrast is what makes the code readable

A QR code is not read by its shape but by the difference in brightness between the dark modules and the background. A QR printed all in one colour will not scan, however crisp the relief is. The safe combination is a light base — white, bone, beige — with a dark code — black, midnight blue, bottle green. The tool calculates the real contrast between your two colours and warns you before you burn any filament.

The other way round, a light code on a dark base, works on most current phones, but some older scanners reject it. If the code is going somewhere busy, stick with the classic dark on light.

The minimum size of each module

Every little square in the code is called a module. Below 1.5 mm, the printer's nozzle rounds the corners and the modules smear into each other: the code stops being readable even though it looks perfect on screen. The more characters your link has, the more modules the code needs and the smaller each one gets for the same object size. Hence two practical tips: use short links — a URL shortener helps — and make the object bigger when the tool shows the warning in red.

Relief height and print time

Between 1 and 2 mm of relief is the sensible range; this tool uses 1.2 mm, which leaves plenty of room for the colour change without stretching the print. On a single-extruder printer you need nothing special: just schedule a pause at the height where the relief begins and swap the spool. The result is exactly the same as with a multi-material machine, except that you are the one standing there.

Which format to choose

The table stand has a sloped face, so it prints without supports and reads comfortably from above: it is the format for restaurant menus and review signs. The keychain is a thin plate with a hole for the ring, meant for sizes between 35 and 45 mm. The wall plaque has two holes along the top for screws or double-sided tape, and it is the natural pick for a holiday let's wifi or for a shop window.

Before printing a whole batch

Always scan the on-screen preview with your own phone before running twenty pieces. If the QR on the screen won't read, the printed one won't either. And if you have put a large logo in the centre, print one test piece first: the logo covers modules and, although the tool automatically raises the code's error correction to compensate, it is worth checking with the real object in your hand.