It's a commercially made unit, but I can't remember who the company that made it is. I got it a few years back when I was still into plastic modelling and I had to bash the kits to make them more scale. 1/32 scale was the largest models I built, so I didn't need a vacuum former much larger than 12 x 12".

If you need some clear plastic for forming, but don't want to get a full 4 x 8' sheet, look at what SIG sells on their website. I've used it for making basic flat windshields and side windows, as well as lenses for instrument panels. It comes in smaller sheets, so you don't have to buy more than what you will need:

http://sigmfg.com/cgi-bin/dpsmart.ex...FV4.html?E+Sig

Look under building equipment, plastic sheets.

Jesse