From web model to printed part
GLB is the format of 3D-asset stores, AR pipelines, AI 3D generators and web viewers. To print one, a slicer wants STL or 3MF — and at the right scale.
The metres problem
The glTF 2.0 specification defines one unit as one metre. Slicers assume one unit is one millimetre. Converted naively, a 25 cm vase becomes a 0.25 mm speck. This converter preselects metres for glTF and GLB and writes the STL in millimetres, so the vase stays 250 mm.
Some tools export GLB at the wrong scale anyway. The summary shows the size before you download; if it is 1,000 times off, switch the source unit to millimetres.
What is kept
| From the GLB | In the STL | In a 3MF |
|---|---|---|
| All meshes, at their node positions | Yes, merged | Yes, merged |
| Solid base colours | No | Yes |
| Image textures | No | No |
| Animation, skinning, morph targets | No — the rest pose is used | No |
| Lights and cameras | No | No |
Is it printable?
Models made for screens often are not solid. Look at the summary's watertightness line:
- Watertight — the slicer should handle it directly.
- Open or non-manifold edges — common with display models built from separate surfaces. Slicers often repair small problems; larger ones need a mesh tool. See watertight and manifold meshes.
Also check thin details: what looks fine on screen may be thinner than your nozzle can print.
Compressed GLBs
Draco and Meshopt compression shrink web downloads but are not supported here yet. If a GLB will not open, re-export it without compression and convert again.
On a phone
GLB conversion works in a phone browser. The Mes3D app for iPhone, iPad, Mac and Android opens GLB files directly, shows them in AR, and exports STL, OBJ or 3MF after resizing or cutting.