Teenage Engineering OP-Z knobs

Teenage Engineering's new OP-Z portable sequencer/synthesizer comes with really nifty ball-bearing hall-effect encoders with a completely flat, disc-like profile. They're nice, but sometimes knobs are nicer.

Conveniently, they come with a standard LEGO Technics shaft profile receptacle, so you can attach your own knobs, so i thought - why not design and print some.

OP-Z Knob G, B, Y and R v3 are a set, and bear the first letters of the encoder color they belong to inscribed on top (thanks