Vortex Sound Research

I picked up an ESQ-1 and am learning how to program it. Saw that someone made a small potentiometer that plugs in to the pedal controller input. Then, you can assign the pedal as a mod source for filter cutoff, so you can use the potentiometer to do filter sweeps. Does anyone sell such a control box (potentiometer with a 1/4 inch output)? Thanks!