Yes, you are right, this thread is 7 years old. In order to form PVC foamboard you need to be able to concentrate the heat in the area you're working on, and be able to quickly pull the source of heat away when you need to. The industrial heat gun is the way to do it. Compound shapes are not feasible without cutting and removing material to allow for the bending. There is only so much that can be done just by heating the PVC.
No one lives forever, the trick is creating something that will.