https://youtu.be/PeTcRm5i0Sc In "Marblevator, Line Follower" a simple ball bearing follows an irregular shaped black line much like the many elaborate robotic line followers. This seemingly impossible feat (the electronics in the ball bearing would have to be quite small!) is accomplished using simple magnetics, a hidden track, a motor and a battery. A magnetic sphere is rotated around the hidden irregular shaped track inside a hollow arm that is rotated by the motor. The black line is located in the center of the hidden track. A ball bearing on the top of the track follows the hidden magnetic sphere which is following the hidden track, giving the appearance that the ball bearing is following the black line. To avoid having to disassemble the model in order to charge the battery, I've included an optional base and inductive charger. Simply set the "Marblevator, Line Follower" on the base to charge it! As usual, I probably forgot a file or two or who knows what else, so if you have any questions, please do not hesitate to ask as I do make plenty of mistakes. Designed using Autodesk Fusion 360, sliced using Ultimaker Cura 4.12.1, and 3D printed in PLA and Tough PLA on Ultimaker S5s.