Thanks, but it's not my design.

That's almost straight from your PDF, with one small siding removed and everything sorted to fit on a 12" shelf. It barely keeps the required sizes for the timesaver puzzle, but I tried to maintain the spirit of the original in a much smaller space. The left leg was the real challenge. All tracks maintain a 2" center-to-center except for the three yard tracks, which were dropped to 1-7/8". That extra 1/4" of space goes a long ways when you're that close to the edge!
At this point I'm barely thinking about backdrops. I'll be happy if I can fit in some simple landscaping, but we'll see how it goes. I'm not even sure if I'll try to use foam, I may just build it right on a piece of plywood. Since this is mostly a test piece to try and work out sensors and such, I may end up tearing things apart a few times as I go.