The included Zip file includes the STLs required to print a 3-Piece Fidget Spinner.
 
The center pieces fit together very snug; and you do have to push down carefully as to prevent breaking the male side. Even so, I put a little dab of glue over the hole and let it drip down before I clip it together. Just don't get glue on the outside of that shaft of your spinner won't spin.