Your body is your mold. I turn my oven on 175 and place the pieces one at a time on a cookie sheet. Then, with simple working gloves, I take the pieces out and place it on the appropriate body part and bend it. The sintra comes out of the over very floppy. You really don't want it that soft, cause the shape with distort. There is a very subtle "grain" to the plastic. If you cut it one way and let it get super floppy, the armor piece will expand horizontally. It will be so bad that the piece is junk. Likewise, if you cut the piece turned sideways, the piece will expand vertically (since you turned it, the grain is the same direction). So try not to leave the armor in there for more than a minute or two. Get someone to help you if you can, so all the edges get formed properly. Doing this will ensure you have a custom & form fitting set of armor. Regardless of the material, the worse thing you can ever have is ill fitting armor that juts out. As for the fumes, I am on set 6 of sintra armor...both 3 & 6mm and have never had fumes problems. Heat guns are great for making one spot on a piece soft to make it fit better. However, if you hold the gun too close or too long, the sintra will bubble up and ruin the armor. For me, the oven makes the most sense. It heats the piece evenly and allows you to do large pieces like a backplate.