Do you have an old tarp laying around? If not, they aren't expensive at K-Mart, Target, MallWart or even an army surplus store. Hang it on the wall to protect it and then you can project to your shrink's content.

But I would say that they came out fine as it is. The top one reminds me (not really like it, but it evokes the memory) of the amphitheater in Cagliari.