Conservation of Angular Momentum Fidget Spinner

thingiverse

This spinner accelerates as it slows down. When initially spun, the magnets move to the outer position. Then as it begins to slow, the magnets shift to the inside position, which causes it to spin faster. Inspired by example prints from [whosawhatsis](https://www.thingiverse.com/whosawhatsis/designs) book, 3D Printed Science Projects*. Use the following: 1 - Ceramic 608 bearing*: The bearing needs to be non-magnetic otherwise the magnets will stick to the bearing and add a lot of drag. They're also available on Banggood*, and are cheaper there. 4 - 10mm cylinder magnets*: Careful, these magnets are very strong and somewhat brittle. Set them to attract each other. Insert from the bearing cavity, and there's a small ledge near the bearing that holds them captive so they don't hit the bearing when they move in. The ledge makes it a bit harder to insert the magnets, but they should move freely once they're pushed past the ledge. * Atomic Filament Amethyst Violet Gemstone Translucent PLA * Atomic Filament Translucent Ruby Red PETG June 2017 Update: I uploaded a new version which works without an expensive central bearing. August 2017 Update: I added a R188 ceramic bearing* version to this thing. I also find the thinner magnets* gives you more flexibility to adjust the speed where the magnets transition. As pointed out by tbuser below, you can also get the magnets at Amazon*.