I did it, I finally did it! I finally finished a piece of test track and put my cart on it. It was the most gratifying part of this whole project so far to fit the cart on and slide it around. I even sat on it, and wiggled a little bit. I'm happy to report that it held my weight and did not break. The supports and the rollercoaster frame felt really solid. We're really starting to go places with this project! The next step is to do some stress testing; finding the near-breaking point of both the track and the cart (I don't want to sabotage all my hard work completely).