Damage Free Whiteboard Foamcore Bracket

I want always wanted to have a whiteboard in my home office, but was shocked at how expensive they are, and was wary of installing once. Then I discovered the awesome Post-It Dry Erase Surface film by 3M, but was worried the texture of the paint on my wall might create an uneven surface on the film, and I didn't want to risk damaging the paint job when removing since I rent my apartment. These constraints all led to the the idea of mounting the film to a piece of 1/2" foamcore, and creating brac