Quick remix of nice knob and D-shaped potentiometers. 

3 versions of 2 heights, 12mm (two left ones) and 17mm, both fit under the DeckSaver

• simplest - no marking

• 1.5mm wide 0.6mm deep notch

• multicolor

Measurement on my old, used Keystep, where the knobs went all sticky (they're not very nice looking either), shows 6mm in width and 4.5mm in depth, 11mm and something in height. There is a little notch on top, but I ignored that. After a few tries, 6.1mm and 4.58 worked fine for tolerance.

Included blender file for easy tweaking.

Quick print in PLA on A1 mini.

In the photos, the final version is the middle one. Red is a terrible color for this, but it is what was loaded, and I hate to reprint things. Rightmost has so little tolerance that I can't take it off anymore (:D), and the left one has too narrow a notch. Multicolor should work fine, haven't tried it.