There are many replacement knobs for the MP Select Mini, but none that I found easy to use. Some have a small dimple, Some have a low profile, Some have a nice knurled surface. But I couldn't find any that had a Low Profile, and a nice Knurled circumference, AND a deep dimple to help keep the knob spinning when doing those slow Z moves.

UPDATE: I made the hole for the encoder shaft a little shallower to make sure it bottoms out. This ensures that the switch will activate when the knob is depressed. So, if you've already downloaded the .stl file, you may want to get the new version.

73 VA3TNE