I've made this to my 3 years old boy, who got really proud for finally managing to properly spin the toy in his tiny hands...
print two pieces without support and glue them together (if you print in ABS, CA glue will hold it nicely)
use three m8 nuts (5/16" equivalent) and one 608 bearing.
tight fit for the 608 bearing. you might need to do a little sanding before placing it.
idea copied from Pulsar Spinner (https://www.thingiverse.com/thing:2108748).
Please, share it if you print it