A thermoforming machine has essentially four parts:
A hard surface with many holes on it
A vacuum pump underneath, which (when activated) sucks air below
A movable platform onto which you attach a sheet of plastic
A heating element
To make a part, you first place an object on the hard surface, and then clip the plastic onto movable frame. The frame is lifted so that it’s close to the heating element, where the plastic is then heated until it’s soft and droopy. You then lower the plastic and frame toward the platform and object, and flip a switch to activate the vacuum. The plastic is then sucked onto your object, wrapping around it.
There’s a lot more to it than that, and Eric did a great job of explaining the ins and outs of using a machine like this. For example, you want the plastic to sag to about the height of the object you’re wrapping. The object itself should be solid, not hollow, or it could collapse and damage the machine.
Eric was also kind enough to bring a number of small wooden objects, and each student thermoformed their own object. He even showed off several parts that he was thermoforming for large drone work.