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 and props to Alexis Jeauffrain for the typography).

OP-Z Knob Alter is an alternative design that apes the upper part of the TE OP-1 encoders - if you're into a more OP-1ish look.

I strongly suggest printing these on an SLA printer, gray resin, to match the OP-Z color. Print them upright to avoid distortion from the peel process. Don't worry about the flat bottom, it'll work out fine with decent support, just sand down the support warts.

OP-Z Knob FDM v3 is meant for FDM printers, and has a completely flat top, with no inscriptions or any detailing, so you can flip it around, and print it top-down.

They're designed for an accurate friction fit - they shouldn't fall out, but should at the same time be easy to pop out. They're not meant to be jammed in hard - if it's too tight, scale them down a tiny bit and reprint.