While building, we ran into a few snags. The biggest issue was the transparency of the plastic. Light could shine through, creating very unreliable readings in different lighting conditions. The solution? Making “double decker” color pieces by gluing them together with a piece of black paper in between. It was more work, but it was successful in making the readings more reliable.
The other snag was the motor. When we made the pieces double decker they became heavier, and the motor suddenly wouldn’t turn. It seemed to strip the tiny spokes on the motor’s head. We had glued the top of the motor into a round hole on our platform, and Tom suggested using the propeller piece that came with the motor. We got a new motor, recut the platform and voila! it worked. Lesson learned— use the pieces the motor came with! (Thanks Tom!)