This is the second version of my fidget roller. This one requires 4 barings but is super smooth and in my opinion much more satisfying as a result. I have also added knarling / texture to the rollers.

It is designed to fit stealthily in any pocket and print in around 30 minutes.

The barings required are 3x8x4mm. I got mine from ebay: https://www.ebay.co.uk/itm/185273084356