This simple STEMFIE project consists of only three 3D-printed parts and represents a spinning top, one of the oldest known toys. A fully-threaded BU2.5 screw serves as the vertical axis, while a BU3.0 washer maintains rotational inertia. Both components are secured in place by a 5 mm STEMFIE threaded nut.
Spinning the top on the screw's rounded head produces a random, wandering motion. To achieve a longer spin time, a sharpened piece of filament can be inserted into the screw's axial hole. For more dynamic motions, try spinning the top upside down.
Typically, this STEMFIE set can be printed in less than an hour, using approximately 2 meters of filament.