Let's design and build cool (but expensive) FPGA based theremin

Wow.  That looks really impressive!

Gorgeous!  Vadim, whatever they're paying you, you deserve a raise! :-)

[EDIT] "Going to search for 3D models and order 3D printing of knobs."  - Buggins

It's one more thing to learn, but maybe get an Ender 3 or clone and play with OpenSCAD or similar.  I've got a nice (IMO) parameterized knob pattern I can give you.  You can't 3D print everything, but sometimes it's fairly amazing what you can print.  Roger sent me a pitch arm that you'd swear was commercially made, dude's totally mastered the medium.