The trouble with IGES and dwg/dxf files is that when he opens them in Rhino, all the 3D elements are exploded. A cube, for example, is broken down into 6 separate planes. This requires lots of extra time to stitch everything back together for rendering. Don't ask why we have to use Rhino, long story that I don't have control over. Re; 3DS, I'll ask him again, but I'm pretty sure he said Rhino will not import 3DS files.