Today I purchased MDF sheets and some plywood. Enough for the treadbox and legs. When I got home, I had a little bit of time so I pulled out the rotozip and started cutting on some scrap pieces of lumber and plywood.
I have to say the rotozip was harder to use than expected. Without a guide, it's going to be difficult to make smooth cuts. I may need to get a sabre saw or band saw. When my younger son got home from work, I had just cut out a small piece of wood from the plywood using the rotozip. I held it up and said it was the beginning of my robot, what did he think. He just shook his head and went on in the house.