Hopper.

thingiverse

https://youtu.be/JVWtLrmafSk "Hopper" is a 3D printed hopping mechanism that utilizes two springs and a compact "mass" consisting of a motor, holder, switch, battery, gears, axle, and cams to propel itself upward with surprising force. The mechanism first compresses the springs before releasing them suddenly, causing Hopper to jump into the air. Inspired by old-fashioned windup and battery-powered hopping toys from my childhood, Hopper was created to illustrate the fundamental difference between potential energy (stored in the springs via the battery, motor, holder, switch, gears, axle, and cams) and kinetic energy (released from the springs and resulting velocity of the battery, motor, holder, switch, gears, axle, and cams), while entertaining my grandkids at the same time. As always, I may have inadvertently left out a file or two, so please don't hesitate to ask if you have any questions. After all, I'm not perfect and do make mistakes from time to time. Hopper was designed using Autodesk Fusion 360, sliced with Cura 4.3.0, and printed in PLA on both an Ultimaker 3 Extended and an Ultimaker S5. One final note: no compensation of any kind is received for the design, equipment, parts, or materials used in this model.