All the small spool holder for the Ender 3 are using a screw type nut instead of a lock nut (probably a new design from Creality) . I created one compatible with the lock nut.

The roller is working with the lock nut coming with the printer. I designed the roller and the lock nut but I didn't print and test the lock nut yet.

Printed on PLA, print them as they are represented.

Default roller size : ~ 36 mm
Small roller size: ~ 29 mm