Thanks for the kind words! I really appreciate it.
The L shaped holder is simply fit inside the slot, with no connections to the Robot, so that when the Robot is moving it can slide with the Dominoes. The steering is very simple: basically each large motor controls one wheel, and the Robot can turn by having one motor go faster than the other.
If you haven’t already, I suggest watching the video I made by clicking on the link. I feel like seeing it in action explains how it works a lot better than describing it with words.