Seems OBJ format Magica Voxel keep color painted inside at the exportation
but these colors are not affectable separatly in a render Engine!

here the file created at the exportation without background obj +mlt+png (of Magica Palett colors - not background)

must create a file with separated colors - for address some different materials : any idea ?
I miss some inspiration now! :)

http://moiscript.weebly.com/uploads/3/9/3/8/3938813/bul.zip

here inside SimLab