Like your work. I do similar things, if I need a custom one off part. 10 turn pots
They are expensive, hard to get (where I live) and also shipping would cost half its price.
have you tried aliexpress? they have blue 10 turn pots and the 10 turn knob's too.
OR maybe with your custom one off part, you can try adding custom lighting.
making a knob glow lightpipe design try adding a custom lightpipe down a transparent plastic axle so the knob will glow with led's. like a red , blue or green glowing dot on the knob. a another idea is the fixd axle with a outer rotating sleeve & ring. the knob face is stationary
so you can add a tactile switch. but the outer ring moves. just more ideas.