What self-respecting Maker wouldn't want to make a fidget spinner with their 3D printer? This is a good quality skate bearing that is designed specifically for fidget spinners. It's a standard 608 bearing. (So of course you can also use it as a bearing for projects with pivoting parts.)
Tons of free models for all your fidget dreams are on Thingiverse and other sites.
3D printed spinners make terrific and inexpensive give-aways to children and adults alike!