I bought a generic vacuforming machine recently:
http://www.ebay.com/itm/171101926273?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649It has a built-in heater and vacuum and a 4" square area for the plastic.
The machine is intended as dental vacuform machine but work fine for model use. It's has a larger work area than the Mattel vac-u-form.
Micromark sells an almost identical model:
http://www.micromark.com/compact-vacuum-forming-machine,11244.htmlHere's the video of the machine in operation:
I used a cheap For Sale sign as the source of my plastic. The first square I cut was only slightly larger than the opening in the holder and the plastic sagged right out. The next three tests were cut to the size (or slightly larger) than the holder; I was pretty sloppy.
For the first test (on the left), I tried a float from an old 1/72 floatplane and a partly finished paper model of a Coast Guard riverboat. The plastic collapsed the boat's superstructure and to add insult to injury, I'd printed the boat on a color laser printer... the heat of the plastic was just enough to soften the toner and make it stick to the plastic. I don't think I heated the plastic enough (you have to guess at the right amount of heating) since it didn't fully form to the cavity. Still, the floats came out OK. The second test (middle) I let the plastic soften for longer. Still not quite filling all the cavity, but even better results. For the last test, I tried vacuforming some photoetch rifle straps (from a Trumpeter kit) and a domed base. The plastic was even softer now, and it fully formed. Unfortunately, there was some contamination on the dome and it didn't form properly. The PE didn't form all that well, either.
Here's a look at the middle test, backlit:
It made a pretty good reproduction. The plastic sign material is OK; there are a couple of spots that are very thin (near the edges). I guess I have to experiment some more.
