The Live DVD build CAE Linux is a complete engineering toolkit for designing, simulating, testing, and creating/printing your own projects. Everything in the build is free and open source software, allowing you to design your device, do multiphysics simulations to optimize it, and generate the code for building it with 3D printing & milling. You can also design and develop your own printed circuit boards, and microcontroller circuits for automation. Not only do you not need to pay for a license for any of this (because of the GNU/Creative Commons licensing it comes with), you don’t even have to install it on your computer; it all runs directly off the DVD, being a Live Disc. This is pretty much the most powerful open source engineering package I know of, if you have any interest in the design and creation of anything from toy cars to advanced robotics, do yourself a favor and check out this build. You can find the download here, although I recommend visiting their home page to learn all about it and see what kind of support resources are also available.