I really like my Kingrinders K6 and K4, playing with them and watching Lance Handrick. So after watching his slow feed video, I tried slow feeding these grinders witht he tilt method and it was great. However after few grinds it was more bothering than enjoyable.

During one cleaning I got idea for slow feeding rubber ring. Few prototypes later it is working good. Not great, but good. There needs to be some further improvement, but you can try it for yourself.

I can speak only for Kingrinders K4 and K6, but whole K series should work and probably even 1Zpresso grinders as well.

Print in some kind of flexible material, disassembly grinder, take out the burrs and push the ring from the bottom to the grinder.

I suggest you to clean it throughly before inserting.

EDIT 16.5.2024: Added 3 hole design. Should align better with internal structure.