Filament Guide Roller for Creality CR10, CR10S, Ender 3, Ender 3 Pro, others

I've tried several of the Filament Guides and Guide Roller designs and none of them seemed to fit right or work well. I didn't want to buy a bearing either so I made this one using a simple nail as the axle shaft.

I can tell you this one is SIMPLE AND WORKS! The concave roller centers the filament before entering the filament feeder allowing the filament to flow smoothly. This improved the quality of my 3D prints!

I threw away the "eyelet" type guide (the one in the photos) and replac