I love the tri-spinners and I have made them for many people. I just don't like having to use 4 608 bearings for each spinner with 3 of them just used as counterweights. I found that 1/2 inch nuts have about the same weight/size as a 608 bearing, so I modified the spinner to use them for counterweights.
I also modified the the knurling in the scad file to have not have partial knurling on the edges. I am a bit of a perfectionist.
Requires:
1x 608 bearing
3x 1/2" nut
Everything press fits without glue. Enjoy!
UPDATE 10 Feb 2017: I modified the scad file to be able to specify normal knurling or inverted knurling. I also uploaded stl files with inverted knurling for 3 or 2 weights.
UPDATE 15 Feb 2017: I modified the scad file to add chamfering to outer edge for a nicer feel in the hand.
UPDATE 20 Feb 2017: I modified the scad file to scale based upon different sized nuts based upon measurements from https://www.fmwfasteners.com/blogs/faq/hex-nut-dimensions. I added models for 3/8" and 1/4" nuts.
UPDATE 08 Mar 2017: I added models for metric M10 or M12 nuts.