Thanks for your response: Here is what I've noticed after trying iges; I created a 2d circle, extruded it, extracted a curve of the top, extruded along a path, then subtracted solids. Exporting iges 3d only then opening it in strata, the subtract solid is not there, the extruded curve is there and the cylinder is hollow.. So then I re imported it into vectorworks and then exported it in simple vectorscript and It worked.. Though the import into strata took quite a while on my g4. It seems quite archaic..