My unofficial specification of the 3d studio format: PDF, TEX
Esto es un simplificador de 3ds, para que cacharros como blender puedan leerlo: simplify3ds

And here the model I were working with
As seen in 3D Studio:

As seen in blender, with an added cube (I've not bothered to get other image)

And now with my program


Still being a rectangle that shouldn't appear, but I don't see any hidden flag. I too have to use the material chunk instead of random color.