We have completed several stages of the Cookie Bot Proto 1. In the first iteration, Corinna built a car to ride along a pair of rails built by Melisa. Donald built a mini car to ride across a the car on a middle rail. The second iteration revised Corinna’s car. Gears and actuators were added to the car, and the mini car was built into the prototype. Sophie and Corinna worked on adding a differential gear system to drive the car. This requires the right and left sides of the car to be symmetric.