EZR Extruder from SeeMeCNC fits on most Creality extruders
As seen in this video: https://youtu.be/1GNDxvxpWr8
This extruder allows a Creality printer to easily print flexible TPU filaments or any filament.
This is a kit you install on your 3D printer. (Not some Ender 3 don't have a set screw removable gear so it may not work on that).