i made one for WORK AWHILE BACK pretty simple only a vacuum source and heat source is all is needed mostly i did a post on how to cut plastic without melting it too,need a wetsaw and change the blade to a fine tooth plastic cutting blade or metal blade ,it needs to be stainless steel or dry it right away second on the water bath ,you need to keep it very cold,one easy way use lots of ice or make a mini refrigerator,cold water cools off the blade and plastic while cutting so plastics wont melt

to make a cheap vacuum forming machine ,heat the plastic in a oven until soft (little hard to do ) and then have a form aready made with holes in it and attach a shop vacuum to it,may need to make a funnel from the hose to the size of your form

I have been wanting to make a plastic body but did not know how, thanks.