GLB to 3MF — multi-colour files for Bambu Studio and AMS
Drop a GLB or glTF model below and get a multi-colour 3MF that opens in Bambu Studio. The tool reads the colours and textures in the file, reduces them to one to four flat colours, and writes each colour as its own part so you can assign filaments in the AMS. Sizing is in real millimetres, and the conversion runs entirely in your browser.
Why 3MF instead of STL for a GLB?
STL holds triangles and nothing else, so the moment you convert a coloured GLB to STL the colour is gone. 3MF is a modern container that keeps geometry and colour, and it can store several distinct parts inside one object. That is what makes multi-material printing possible: Bambu Studio reads each part, shows it in the object list, and lets you point it at a filament slot. If your GLB is a single-colour model, STL is simpler and smaller; if it has colour you want to print, 3MF is the format that preserves it. The GLB to STL converter covers the single-colour case.
Material colours versus texture colour reduction
GLB files carry colour in one of two ways, and the tool offers a mode for each.
- Material colours. The model is already split into separate materials, each with its own base colour — common for hard-surface models, logos and low-poly assets. The converter groups triangles by material and makes one part per colour. This is a clean, lossless split as long as the model has four materials or fewer.
- From texture or vertex colours. The colour lives in an image texture or in per-vertex colour attributes, and there may be thousands of distinct shades. The converter samples the colour at the centre of every triangle and runs k-means clustering to collapse those shades into one to four representative colours. Every triangle is then assigned to the nearest cluster. This is how a photographic or gradient texture becomes something an AMS can actually print.
Choosing the right mode matters. If a model already has four tidy materials, use material colours and the split will be exact. If it has a texture, use the texture mode; on material colours a textured model usually collapses to a single flat colour because all of its triangles share one material.
Reducing a texture to four colours with k-means
k-means is a simple idea: pick k starting colours, assign every triangle to the nearest one, then move each colour to the average of the triangles assigned to it and repeat. After a dozen passes the colours settle into the dominant shades of the model. Because the result depends on the starting points, the tool uses a fixed seed, so the same file always produces the same four colours. The stats card lists the resulting swatches and the share of the surface each one covers, which tells you at a glance whether a colour is a large region or a few stray triangles. If a swatch is under a few percent, it is probably noise and you can lower the colour count.
What to check in Bambu Studio
Import the 3MF with File → Import. The model arrives as one object made of several parts, listed under the object in the plate view. The colours are stored in the file, but whether your slicer version maps them to AMS slots automatically can vary, so open the parts list and confirm that each part is pointed at the filament you want. If a colour looks wrong, right-click the part and set its filament. The Bambu Studio 3MF import guide walks through the object list in more detail. Slice, preview the filament changes, and print.
Limitations to know about
- Textures become flat colours. Photographs, painted-on detail and soft gradients are reduced to solid regions. You get a stylised, poster-like result, not a replica of the texture.
- No gradients and no painting. A 3MF from this tool has hard colour boundaries between parts. Use the slicer's own painting tools if you need to add colour by hand afterwards.
- Four colours maximum. This matches an AMS Lite. More parts would mean more filament changes and more waste than most prints justify.
- Separate parts, not one painted skin. Each colour is its own closed solid, so the model is watertight part by part; there is no single textured shell.
Orientation and size
Exactly as on the STL page, the converter rotates a Y-up GLB into the Z-up orientation slicers expect, and scales the model to the target size you choose. Because 3MF stores millimetres, the numbers you see in the stats card are the numbers the slicer will show. Keep the model comfortably inside your build plate, and remember that fine colour regions smaller than a nozzle width will not survive slicing.
Questions
Does my GLB keep its texture in the 3MF?
No. Textures are reduced to one to four flat colours, one part per colour. Gradients and fine texture detail become solid areas.
How many colours can I use?
One to four, to match an AMS Lite with four spools. Fewer colours means fewer filament changes and less waste.
Will Bambu Studio assign the filaments automatically?
The colours are stored in the file, but mapping them to slots can differ by version, so check the parts list and assign a filament to each part.
Which colour mode should I choose?
Use Material colours when the GLB is built from separate materials. Use From texture or vertex colours when the colour lives in a texture or in per-vertex data, so it is sampled and reduced with k-means.
Is the GLB uploaded?
No. Everything runs in your browser, so the model never leaves your device.
Can I paint the model afterwards?
No. The converter produces flat colour regions, not a paintable texture. Use the slicer's painting tools if you need to touch up areas.