Blender - Blender is the open source, cross platform suite of tools for 3D creation.
Autodesk DWG TrueView - Get a free DWG viewer to view, open, edit, and convert .dwg files, the native file format for AutoCAD files. DWG Trueview includes DWG TrueConvert.
Sculptris - Sculptris: Enter a world of digital art without barriers.
LiteCAD - Create, edit, view, and print 2D CAD drawings using the file formats: dxf, dwg, shp ;Download-Size...
ZBrush - ZBrush is a digital sculpting and painting software solution.
ZWCAD Viewer - Cross-Platform .DWG | .DXF | .DWT R12-2013 Viewer