https://youtu.be/JVWtLrmafSk "Hopper" is a 3D printed hopping mechanism. Using two springs and a "mass" (the motor, motor holder, switch, battery, gears, axle and cams), the mechanism first compresses the springs then releases them to propel the mass upward to an abrupt stop causing Hopper to hop. Modeled after windup and battery powered hopping toys from my much, much earlier years, Hopper was designed to demonstrate the difference between potential energy (energy stored in the springs via the battery, motor, motor holder, switch, gears, axle and cams) and kinetic energy (energy released from the springs and the resulting velocity of the battery, motor, motor holder, switch, gears, axle and cams), while entertaining the grandkids as well! And 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 Cura 4.3.0, and printed in PLA on an Ultimaker 3 Extended and an Ultimaker S5. One final note, I receive no compensation in any form whatsoever for the design, equipment, parts and/or materials used in this model.