fiberglass resin..I think you can get it at places like home depot, or maybe some car places like auto zone. I'm not sure though, you should probably call around. Also, you need to sculpt out the helmet first then apply the fiberglass resin & cloth. I heard that stuff is pretty heavy too. Oh, and you don't wanna breathe in the fumes, its best to use it outside although its pretty chilly right now, or atleast where I live. I never used fiberglass resin before, so I can't really say much about it.