Practical uses of this technology for the home hobbiest are probably fairly few. My brother in law used a similar process to repair boats. He would make a mold of the location on a good boat to make a perfectly fitting patch to repair a damaged boat. He would place the mold on the outside of the hull and repair the damage from the inside with bondo putty and rough layers of glass. Exterior sanding was minimal afterwards and the repair was invisible from the outside. Modern aircraft are made from bonded layers using the technologies described in these videos.

It looks like a process for making a shell or object from a base object. You lay down this PVA stuff before hand so the Epoxy doesn't stick to it which is cool looking. But then they go over the layering process with the Epoxy and Fiberglass. Not much to look at if your not into Epoxy.

just wondering, what does this actually DO?

I don't have sound, but this for fiberglassing right? I've been looking for a guide on this.

Neat. What's it for?