An updated Extruder Knob. I designed this for the Ender 3, but will fit any compatible stepper motor.
I made this extra tight to fit the shaft as the ones I tried before eventually loosened up and started slipping. You can adjust the fit by scaling the model if you wish, but at 100% it's perfect on a tuned printer.
The one in the pic, I did a filament change on it - just because. But print it in any PLA of your choice.
Update: March 30, 2019 - Added another version with an extended shaft if you want more clearance to view for filament changes.
Hope you enjoy.