I wanted something with grip and that would allow fine control of an encoder as well as being easy to push.

I made this specifically for this rotary encoder and some other similar ones (PEC12R-4225F-S0024).  

However, it seems to fit a lot of different encoders I have lying around. 

I've also included a fusion 360 project which is fairly parametric. You should be able to easily change:

• The diameter of the knob
• The height
• The cutout to match other encoders that may not fit