Creality CR10/Ender 3 M10 thread Extruder for Flexible Filament.

thingiverse

So the original file was everything I needed it to be: an extruder piece that constrains the filament path more than the stock one, and uses one of the nine spare PC4-M10 couplings I had left over from the 10 pack I bought to replace the one that came with my printer a month into owning it. The changes I made were: adding a hexagonal indent so you can use an M3 nut and screw for adjustable spring tension, and added clearance for the screw head on the hole next to the threads because the original file lacked this. As stated in the original thing, print standing up with the hole for the threads against the build plate.