LibreCAD

LibreCAD is an open source 2D CAD application for Windows, Mac and Linux. The app is great for industrial designers, but anyone who wants to learn how to make 2D CAD drawings will like this program. For a free software, LibreCAD gives you a lot of tools to work with. New users will be able to create basic drawings, while advanced users can make engineering plans with the software. Layers can be added, ideal for complex drawings. The provided tools are sufficient for producing high precision drawings. You can start drawings from scratch. But it is also easy to put in splines, ellipses, arcs, lines and circles. A single item can have several iterations. For instance, you have 4 modes for a rectangle parameter.