Useful Software Packages
This is the palace to put details of software packages that are useful for RepRap (like CAD programs), but that are not part of the RepRap project itself. Give a paragraph or so of explanation on each package and a link to its home page. Please also say what platforms it runs on, what licence it is distributed under, and whether it is free.
Mechanical CAD software
Art of Illusion
Art of Illusion (AoI) is a 3D graphics design tool, but it is good for engineering design too. It has a very easy and quick-to-learn user interface. The [AoI homepage is here]. AoI is freely available under the GPL.