Is there a tool out there to do this? My CAD package outputs STLs, but my CAM wants a DXF or HPGL file. I could write a converter myself, but I'm really hoping I don't have to. It seems like a pretty straight-forward conversion for 2.5D designs - search for common edges between two polygons where the polygon normal vectors are normal to each other, and output a line segment corresponding to the common edge. Surely someone has done this?