Leif, this is for you, and the rest of us. Bear with me I'm trying to organize these ideas logically, but 2 night shifts in a row have me dazed. There is a time in aircraft building that flat sheets of clear acetate just won't do it and we want the full bubble. Especially on modern jets. I took the plunge last year and built a vacuform machine. It is not fancy at all just a box with little holes in the top and one big one on the side for your spouses vacuum cleaner hose attachment. I put some gasket material around the edges to get a little better seal, but this thing works ok without it. The box doesn't have to stand up to the vacuum of space and I think you can build one out of a study cigar box as long as you can get the hose attachment to fit fairley snug. make your work surface about 1/2" to 3/4" bigger than your anticipated largest project. Then drill 1/8" holes on the top, mine is a piece of 1/4" masonite in a fairly regular pattern. It doesn't need to be exact. I sealed the inside with tub and tile caulk I had laying around, but you can use about anything. The trick is to minimize as many leaks as possible. You want all the air sucked thru those 1/8" holes on the working surface.