Well, y'see, I live in Australia, and it does get very hot over here, and from what I've just heard from a friend of mine, the material that the DP Helmets are made from is a soft vinyl, and it tends to warp in heat. So before I heard that, I figured that vaccum forming it out of solid plastic might be the way to go. Now I'm not so sure. Remember I am new to costuming, and I am getting confused.