Lime is a super compact & simple extruder. The gears are from the DXC extruder by Phaetus, Devil Design, and Creality.
It's so simple that there are only 3 parts to print, and none of them require supports.
Lime looks like this👇
K1's gears might also work, but I haven't tested them. Note that the DXC gears have helical grippers for the filament. It is probably superior to the ones on K1.
Feel free to make modifications to this design and ask for different formats of the CAD.
Link to DXC's github: https://github.com/Phaetus/DXC-Extruder, and special thanks to DXC's creators~