While Google’s Sketchup remains king of the free quick-and-easy 3D modeling programs, there is a severe lack of free or open source 2D CAD programs available. I recently found out about DraftSight, which is being developed by Dassault Systems, which is best known for SolidWorks.
DraftSight is free 2D CAD software that allows users to create, edit, and view DWG files. The only requirement is that users activate each installation with an email address the first time a file is saved or printed. After that, the program must be reactivated in the same manner after 6-months and then at 12-month intervals.
With DIY CNC machines becoming easier and more affordable to build, free or low-cost 2D CAD programs are in increasingly high demand. Even more surprising than the program being free is that it is being developed for Windows, MAC, and Linux operating system platforms.
I have just begun learning to use DraftSight, but thus far I like what I see, especially given its $0 cost.