This fidget design came to me during a conversation I had with the Mrs about bygone toys I loved as a child. One of which was the He-Man Masters of the Universe ATTAK TRAK vehicle:
https://www.youtube.com/watch?v=EZgh36Jvtwc (Accessed 27/08/17)
I don't know why it popped into my head but I can still remember being amazed by the way the 'wheels' worked. I then decided to try and design a fidget that would encompass the same mechanism as I felt it would lend itself to quite an unusual hand toy.
Since my wife's name is Jo and mine is Sam, I decided to call it the 'JAM fidget'.
The entire print (3 pieces) should take just a few minutes either side of one hour and requires just one bearing. I chose to use an ABEC-11 bearing in mine but only because they were the only ones I had laying around.
Here's a video of it in action: https://www.youtube.com/watch?v=dLkO2KMYMG8
Anyway, I hope you have fun with it. It would be great to see if this newest version takes off -- if you do like it, please post a 'Made'.
There's really very little to say about assembly. Just bear in mind that the bearing and gear sleeve is an interference fit and will need a fair amount of force to overcome it. Also, be sparing with the superglue -- if not you run the risk of gluing the gear inside to the housing.