Using two Arduino sketches and one Arduino Uno, it is possible to turn a few 5v quadrature encoders into a USB keyboard which types keystrokes in response to turning the knobs.  This project does exactly that. I'm using it for X, Y (and eventually Z)-axis control on my CNC.js-powered Milling Machine.

Todo:

• Add a few OLED displays for a rudimentary DRO.