Whats the best building surface? I know the obvious is a large flat one, but I'm working with limited space. The kit gets here tomorrow and I was cleaning my room so I could start building right away. the only problem is, that there is no perfectly flat surface that I can use to start building on. Do I just need to find some good cardboard? I was rooting around in the garage and spied a hollow core door in the rafters.... Would that be a good surface? Now I jsut need a good arguement for why I should be allowed to poke holes in the door... lol or I could just take one off the hinges and see what my mom says then.