For vacuumforming, I use medium sized sheets of plastic sandwiched between two wooden frames and heated in my kitchen oven. These heated sheets of plastic will be pressed over a mold on a vacuumtable, outside of the oven.
STYRENE, ABS, and PETG are the most common types of plastic sheets that I use to vacuumform parts with.
Styrene is also know as "Polystyrene" or "HIPS" (Hi-Impact Polystyrene).
Styrene usually comes in a matte color, heats up easy in an oven, and takes paint very well. But, styrene is not as flexible as ABS plastic.
ABS stands for Acrylonitrile Butadiene Styrene. It basically a form of Styrene plastic with an added elastisomer.
ABS plastic comes natually glossy , and flexes well under pressure without snapping or breaking as easy. Paint has been known to flake off the surface over 10 or 20 years time if flexed and used enough.
PETG is a nice vacuumformable clear plastic. Affordable too. It has some of the same problems with overheating and boiling that ABS has. If you watch the plastic closely, you will get the hang of PETG's heating time within a couple of tries.
I recommend you using styrene if this is your first time vacuumforming. ABS plastic does not heat up as evenly as styrene, and "hot spots" (that can happeing in the heating process) can ruin a vacuumpull. Using the 'easier to use' styrene will save you time and money in the long run if this is your first time.
01 Buy the sheets of plastic from a local plastic supplier. I use www.sabicpolymershapes.com as my supplier (Atlanta, GA - USA). They cut the plastic to size and ship directly to my door. You can purchase styrene or "polystyrene" in an .080 gauge (OH-eight-gauge) thickness, or a glossy ABS plastic in .090 guage thickness.
02Cut the large sheets down to fit the wooden vacuum form frame, and allow 1 -to- 2 inches of play on all sides. Notice that in the picture I have some EXTRA left over from the cutting . that is due to the fact that my Vac-frame is only 21 x 24 inches. I had to go with what fit in my oven.
03Heat up the kitchen oven (450 degrees Fahrenheit, 232 degrees Celcius) on the bottom burner . Do not use "preheat" (the top burner burns plastic and heats up the BACK plastic too quickly)
04Position the plaster mold on the vacuum table. You can learn how to make plaster molds in the Casting Plaster Molds section.
08Test the vacuum-form machine and make sure a good amount of air is being sucked into the machine. Do not allow the plaster cast to obstruct the vacuum hole as it will hinder the vacuum-forming process. You want air to go into the hole so that the plastic will be VACUUMED onto your plaster cast. Use small chunks of wood to keep the plaster off the hole, if need be.
Now lets HEAT THE PLASTIC.