This is a roller bearing I designed because I was tired of printing support for ball bearing designs.

This was meant to be more of a fidget than a bearing that you'd use on something (that's why it has textured rings), however, it works very well as a bearing under modest loads.

I have scaled these up and down.
Smallest red bearing in the photos is 30mm outer diameter.
Larger red bearing is 40mm OD
Green and Glow Bearings are 43mm (native size).

I have scaled up to 70mm and they print fine. The larger (60mm or larger) sizes print without any fusing of the rollers. Curiously, the smallest (30mm) bearing spins the longest. It fused initially but once separated, spins amazingly well.

Please post your comments and makes!

Do not be alarmed if the rollers fuse slightly to each other. I break them apart with small needle nose pliers. Just insert the pliers in to the gaps between the rollers and twist the pliers. This is usually enough to separate them. Do this for each roller and the bearing will spin freely.

Note: I have found that Hatchbox PLA prints very well. However, Hatchbox Silver PLA tends to fuse far more than other colors, or even other brands. If printing this bearing in Hatchbox Silver PLA, you might have to print it at 50mm or larger