QCAD is a free computer-aided design (CAD) software for 2D design and drafting. Developed by RibbonSoft
License: Free Personal
Apps available for Mac OS X Windows Linux
LibreCAD is a free Computer-aided design (CAD) application for 2D design. It works on Linux, OS X, Unix and Windows operating systems. Developed by Ries van Twisk
License: Open Source
Apps available for Mac OS X Windows Linux PortableApps.com