If you want to play around a bit with the RK-002 input functions in the DUY portal, this board provides connection points for buttons or even an encoder (not at the same time by the way)

The RK-002 has two inputs available which you can code to do all kinds of things; Maybe you need just a patch change up/down, start/stop button, a MIDI channel switcher, volume changer, velocity scaler,…,… whatever you think is handy.

Please note: The is of experimental nature, tested with recent versions of the RK-002 only.