These are the Airbus A320 - Home Cockpit Knobs by MartinAM, edited to fit on a Behringer X-Touch Mini. Special thanks to Martin for making them, and for allowing the release of this modification!

On the inside, these use the knob fitting by gergreko, which works well with the X-Touch Mini's 6mm encoders. Thanks to his design, you can hopefully install the knobs without much modification.

The knobs on the picture were printed with PLA on a Prusa i3 MK3S. I added a thin piece of cardboard on the inside wall of the knob fitting to get the knob to sit tight on the encoder, so that it can't easily be pulled off. Additionally, I filed off a small bit of the round bottom plate to prevent it from rubbing against the X-Touch Mini. This probably varies depending on your printer and material. If you own a printer and would like to improve this, please share your results, I'd love to link to them (or update this thing and give you credit).

Update v2

Kudos to bLindye, who improved the knobs by extruding the inner part some more. If you print them in PETG (PLA might work too), they now fit perfectly without any modifications!