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.
Cura - Cura aims to be a end solution for personal 3D printing with RepRap based machines.
Autodesk Design Review - Design Review lets you view, mark up, print, and track changes to 2D and 3D files.
Slic3r - STL-to-GCODE translator for RepRap printers Here comes Slic3r! Its features are: - speed
LiteCAD - Create, edit, view, and print 2D CAD drawings using the file formats: dxf, dwg, shp ;Download-Size...
MatterControl - MatterControl is a free, open source app that lets you organize and manage your 3D prints.