There is not much more I can say about the vacuum source. A shop-vac is not the only way but it works well and I had one available. There are other, better sources of vacuum but I have not experimented with any as of yet so can't comment. For more on this subject I recommend the book listed at the end of this post.

Next item is the frame for holding your material to be formed while you heat it and form it. I make mine from aluminum angle stock available at most hardware stores. Bend to the proper size and pop rivet or nut and bolt the last corner to hold it all together. The three frames shown below all work with the 9x11 box depending on the size of the part I'm forming. One is slightly larger than the box, one is the same size as the top of the box, and one is much smaller for those really small parts. When using a frame smaller than the box itself you must tape off the unused portion of the forming bed so that a seal can be formed by the hot plastic. (continued)