Insulation foam board lining.

More for a test of dimensions I tried to make some of interior linings out of insulation foam boards called Styrodur. It’s easy to shape with knife or saw and can be nicely sanded to smooth surface.

However this looks interesting this type of material would need a coat of polyester or some sort of reinforcement! Nevertheless I think it is still to soft for use, it can’t be a part of the structure to hold the overhead.