Sleek tri lobed fidget spinner with smooth chamfered edges and no hot spots. Uses standard R188 bearing It uses 12mm balls for the weights that can be found inexpensively online in places such as auction sites. The dimensions of this spinner are 30mm radius from center to outer edge.
1) 3D printing is great but size may vary slightly. Because of this sometimes bearings/balls may be a little too tight. If this happens a light scrape from a hobby knife in a circle in holes will usually open up enough. Do a LITTLE at a time and try, too much and things will be too loose.
3) Press in balls. Put a few drops of cyanoacrylate (super glue) on the BALL and let it drip into socket (it is easier to scrape excess glue from the ball). After dry scrape any excess glue from ball.
4) Insert 1/2" x 1/16" thk O-ring into groove. Press in bearing, you may need a bearing press (or after O-ring inserted open slightly by cutting rubber with knife while in spinner to keep shape). If the spinner wobbles press in more in the high areas until straight. (If you used greased and/or rubber sealed bearings it will not spin long. Remove seals and de-grease for best results.)
Slightly taller caps will be needed due to bearing seat, you may need spacers depending on caps.