The basics of vacuum forming plastic is that you have a mold of the shape you want, and you heat the sheet of plastic up enough to get soft, and then use a vacuum to suck it down tight to the mold while you let it cool. The plastic then stays in the shape of the mold. Many common things are vacuum molded such as packaging for products, point of purchase displays, tool holders, airplane canopies and lots of other things.
The machine has a lot of really great features for making the same part over and over and getting it to turn out right. The instructor told me that the basics are the 3 T's; Time, Temperature and Tooling. There are functions on this machine to keep the plastic from sagging too much, and to help release the plastic from the mold with a puff of air. It a really cool machine.
First, you need a form you want the plastic to take on the characteristics of. Then you consider the material to decide what temperature to set the infrared heater to and how long you will be heating it.
There seems to be some art to the whole process for complicated shapes, but for simple shapes like we did in the class it seems pretty easy to do.
I've included some examples I found on the web, maybe it will inspire someone to want to vacuum form something.
You can make pretty much anything at www.techshop.ws so take a class and get started.