For a very inexpensive vacuform you probably already have most of what you need. A simple cloths iron can supply the heat. A vacuum cleaner the vac. A wooden box with holes drilled in the top and a large hole on the side to fit the vac hose should be well within most modelers' abilities. That just leaves the frame for holding the plastic, simply buy a window screen frame replacement kit ( about eight dollars). Make the frame slightly bigger than the top of the box (need 2 of these). Use binder clips to hold the plastic between the 2 screen frames. Put a bead of silicone around the top of the box and you're ready to go. I'll post some pics of the simple one soon.