What is it? Vacuum molding uses the suction of a vacuum to pull a thin sheet of heated plastic or ABS tightly over an actual object, or replica of an object. The plastic cools and takes the exact shape of whatever object you set into it, allowing you a perfect mold of the object. You can now make as many replicas as you like, allowing you to rapidly prototype any number of objects, any number of times.

A professional one…

Advantages Cheap Very quick, the mold forms in seconds Can make prototypes for many different companies in minutes, without wasted money. Mold lasts through thousands of uses. Easy to DIY

Disadvanteges You must have one of your object that needs prototyping, so you must spend the time to build one. Can only be filled with Alumilite or a quickly setting rubber not something stronger like ABS, because that must be heated.

To get a part molded this way, I found most companies charge about 300 dollars for just the one mold. You can DIY for about 100 dollars, and have the actual machine.

Basic video of the process 33U

Vocab! Additive-Adding material to a product Subtractive-removing extra stuff like the plastic around a mold Compressive-taking files that are very big and making them smaller.

Sources