"This Bondo brand Fiberglass Resin consists of only a one-part solution and has the hardner already mixed in."
PLEASE READ THE DIRECTIONS ON THE CAN FIRST!! No it dosn't!! It comes with the hardener seperatly and YOU have to mix it in your self. It is NOT already mixed in, repeat NOT already mixed. You'll have a big mess if you use the resin directly out of the can without using the hardner as it will never cure.
I don't want to see you get into trouble doing this.
Also it DOES heat up a little when curing, that is the normal chemical reaction that happens when the curing process happens when you mix the resin with the hardener. If your fiber glass resin isn't too thick, 1/4" or more, it won't heat up enough to do any "possible" damage. I lined my PVC ANH trooper helmet using the same resin fg stuff you have in your pic and I got it a 1/2" thick puddle of resin in one part of the helmet and man was it HOT!!!!