Fidget Spinner Gyroscope 12 1/2" Inch Balls

75 mm dia circular spinner with twelve holes at the rim for 1/2" chrome steel ball bearings (slingshot ammo). Standard 608 skate bearing (8x22x7mm). Scale as necessary for a tight press fit for the balls. Adhesive will throw off the balance. (Just a thought: You might even try 50 caliber lead balls used by muzzleloaders.) Try printing with three perimeters, a 20% hex infill, and zero top and bottom layers. This will expose the hex infill (as in the photo), which you use a soda straw to blow against to accelerate the spin. Human power only! DO NOT use an air compressor! Ask your science teacher about centrifugal force. Using a kerosene-lubed Yellow Jacket ceramic bearing, and with all twelve 1/2" balls installed, I got a five and a half minute spin. Fidget & Bearing buttons - https://www.thingiverse.com/thing:2376598 - Includes hints for making your fidget spin longer. Fidget case - https://www.thingiverse.com/thing:2410241 - To keep your competition fidget pocket-lint free.