.stl (already supported)Full colour 3D models on Wikimedia projects would be a really great addition, .obj and .ply which all only display shape (adding .MTL support would allow .obj to display colour but would be really fiddly), AMF alsothere are 10,000 of openly licensed full colour 3D models available online.
**File format options**
# AMF supports material, texture, constellation and metadata, allowing you to show full colour models.
https://en.wikipedia.org/wiki/Additive_manufacturing_file_format
# If supporting AMF isn't possible for a some reason 3MF may be an alternative open file format that could fulfil the same need
https://en.wikipedia.org/wiki/3D_Manufacturing_Format
# .obj and .ply only display shape (adding .MTL support would allow .obj to display colour but would be really fiddly and not user friendly at all)