Foamsmith

Used often by artists and Cosplayers that create interpretations of objects, weapons, accessories and, in most cases, armor pieces out of foam materials and it's many variants under a commited cycle or not.

"Foamie" being the product name that it's given to the top used type of them that you can find in the art alleys from your local stores.

Fact being that it's actually named EVA Foam or Ethylene Vinyl Acetate Copoplymer Foam, term heard often by individuals who partake in these arts.

Other instances of the foams used go by, but not all: Styrofoam, Polyethylene Foam & Upholstery Foam. Surprisingly, the fair majority that you will find inside the work of many can be easily found on your households, just not prepared to create stuff with it.