This was more of a novelty than a practical tool, but still pretty cool nonetheless. A shelf on drawer runners holds a thin-ish sheet of plastic up to a nichrome wire heating coil up in the top of the box (lined with cementboard and sheet metal for insulation).
When the plastic is heated, it softens up, and the shelf holding the plastic drops down onto the bottom platen, which has a ton of tiny holes. The vacuum pump (under the machine) draws air down through the holes, sucking the plastic sheet down onto whatever is on the platen, creating a ‘shell’ over the object.
The whole machine is a pain to operate, because the nichrome heater requires 220v. I don’t have a 220v outlet out in my garage, and kludging a solution to get it running properly is pretty scary, so it mostly sits unused.