After failures with the contacts in my push buttons, I returned to the idea of using capacitive touch sensors. What is the challenge? I need something conductive right under the plexiglass that doesn't block the light from the LEDs. Today I think I may have found the solution: ITO (Indium Tin Oxide) Coated PET Plastic. ITO coated plastic is conductive AND transparent! So my idea is to place this under the plexiglass and run wires down to the Arduino for capacitive touch. I hope that this is the final solution for turning the pentagons into keys for the instrument.