For images I found I can just add the file extension “.png” or “.jpeg”, but what extension should be used for meshes? Neither .fbx nor .obj seems to work; blender can’t open the file.
Well that my friend is a json file, that is also not the mesh, you might need to dig a little deeper to download the original mesh used
Roblox uses an internal mesh format that’s well documented if you know where to look on here, another tip, use /v1/asset?id=, you’ll get the source asset with that