It might be possible to do a sort of heat gun vaccuforming type operation with sintra. When you heat it with the gun it tends to get very soft and stay that way for a little bit. I could make a wooden form in the shape I need for that particular piece of armor (a Snowtrooper chest plate fro example), trace it in pencil on the sintra, heat it up using the pencil marks as a guide and then press it down over the shape. I would use a wooden block or something similar to press it down over the "mold". I haven't tried it but I'm sure I could get somewhat of a nice effect from it. Call it press forming. What do you think?