We made some panels before there were any available for sale. We used some foam core presentation boards and some of the metallic thin insulation that is often used in HVAC installations. The we used some 2" wide velcro to secure it to the roof. So far they have stayed in place. It's critical to clean the surface with solvent, like alcohol, before applying the velcro. These panels have helped quite a bit with the a/c load and staying warm in the winter. The heater is much stronger than the a/c though. I have some photos of this if anyone is interested.