Hello, I restore plastic muscle car grills, warped part you need heat and weight on it. It is hard to explain how to do it but I use a heat gun, heat the part up until you feel the part is not super hard but watch not to heat to much then flatten by hand or use some weight.Some times you can use weight on the part and just heat up the weight that works sometime to, but again do not over heat or the weight may mark the part. For epoxy I would recommend "PC7" find it in most hardware stores, plastic welding is ok if you are really good at it, I have done it but again do not over heat the part. That is it for now just beware of how much heat you are using. I have been grills now for about 10 years and some times I could not fix some parts and had to fabricate a new piece for the part I was working on. I hope this will help you for what ever you do.