Vacuum-formed plastic is everywhere, from take-out coffee lids and blister packaging to airplane interior panels. I use vacuum forming to make toy prototypes in my own shop. I usually use a professional machine, but in a pinch I’ve used this ultra-cheap, homebrew rig with great results. You just need to build a simple wooden frame and a hollow box, and then your oven melts the plastic and a household vacuum cleaner supplies the suction. I’ll show you how to build the device and then use it to create a tiki mask that also makes a great Jell-O mold.