Yes absolutely.
I myself have made masks from leather, paper mache, plaster, plastic, cloth etc.
I have seen others make them from old gas masks, neoprene, laytex, metal, and one ingenious fellow made some from wire coat hangers, with fiberglass cloth sewn to it, covered then in resin fiberglass, covered then in car bondo, with various wood and metal bits.
If you ever have a question feel free to ask me, or send a very politely worded note to an artist whos mask you admire and they will usually tell you what its made of.