So... we ditched the heat inserts...

We glued the pulleys to the shafts. We also lengthened the linkage arms and created supports to provide more compression against the pipe walls. On the electrical side of things, we redesigned the robot's body to accommodate cleaner and tighter wire management. This meant fitting our step-down converter, battery, and Pi Pico in a shared compartment and the motor drivers above them.

Since the compression force produced by the stepper motors and the friction produced by the material of the wheels could not support the weight of the robot, we also added two bearing casters to steady the bot as it traversed through the pipe. Since the weight of the robot was incapable of being supported by our steppers, it was unable to navigate vertical pipe segments, or ones over a slight incline.

After a grueling week of assembly and stress, we came up with the following final prototype: