So i need to build this cherry picker. There will need to be two different models. One of the wheels and "chassis" (or whatever you would call the part housing the engine and mechanics) and another that is just the basket suspended by the arm. What materials should I use? I'm thinking just foam for the bottom part because it doesn't need to support any weight, but the crane arm will need to hold itself up as well as the puppet. It also needs to move to various positions for animation. 
Also, how should I paint to avoid a textured look in the foam? Should I even use the foam? Thanks fellow stop-motioners! I'm uber stoked to be finally animationg with puppets instead of legos!!
Cheers-
Sam Lowe-Anker