what about the gel form for mask

I think you're asking about Hot foam and cold foam. While Hot foam is rubber product vulcanised (heated) in an oven and cold foam is formed by a chemical reaction, they both give you a foam rubber end product. Hot foam (foam latex) is stretchier, and can made softer. Cold foam (synthetic rubber) is very similar, but isn't as soft at it's best, and while soft, stretches less.

By gel form do you mean gelatin skin, maybe foam gelatine? These are excellent prosthetic materials, but they do present some challenges due to melting and gluing them on.

I hope this answered some of your questions.