STL vs 3MF: which to use

2026-09-01 · 6 min read

If you're printing a single-color object, the debate is irrelevant. If you're printing a QR code, which needs two colors to work, the format decides how much manual work you'll have to do.

What each one is

STL

Born in 1987 for stereolithography. It stores exactly one thing: a list of triangles. No declared units, no color, no materials, no part names, no structure. Each triangle repeats its three vertices, so files are bigger than they need to be and vertices aren't welded together.

3MF

From 2015, driven by a consortium of manufacturers. Internally it's a compressed file (a ZIP) with XML documents: the mesh, the materials and colors, units declared in millimeters, several independent objects and their position. It's what Bambu Studio, PrusaSlicer, OrcaSlicer and Cura use internally when you save a project.

Practical comparison

For a QR code, the difference is concrete

With 3MF you download one file, open it, and you already have the base and the code as separate pieces, each with its color assigned. Assign a filament to each and print.

With STL you download a ZIP with two or three files, import all of them, make sure they land in the same position (if one drifts a millimeter, the code prints misaligned), and assign materials by hand.

So, when to use STL

• Old software that doesn't open 3MF.
• Some online printing services that only accept STL or OBJ.
• Workflows where you'll modify the mesh in CAD software that works better with STL.
• When you're printing in a single color and it doesn't matter.

What about OBJ, AMF or STEP?

OBJ supports color via texture but no piece structure for printing; AMF was the attempt before 3MF and almost nobody uses it; STEP is parametric geometry, excellent for CAD and unnecessary here. For home 3D printing in 2026, the real choice is between STL and 3MF.