CAD is one of those hold-out areas for windows which is actually kinda strange because when it comes to non-CAD 3D software a lot of the big names are UNIX-native and got ported to windows at some point: Houdini, Maya and Blender all got their start on IRIX and run perfectly fine on Linux, 3dsmax... well, Autodesk. Somehow they started out writing their software for DOS and became dominant in the CAD market despite that.

Speaking of Blender did recently get its feet wet with some CADish constraint modelling but I'm sure it's nowhere close to where it's usable for engineers. If you're an artist modelling something mechanical it's damn useful, though, and it might be sufficient for some light hobby usage, that is, to feed a 3d printer.