This is a gameboy triple oscillator. basically meaning, its 3 gameboys acting as separate oscillators. each seperately tuneable, and synced together with a common oscillator driver. With Cv inputs on pitch and volume. A lot of other adjustments are made through the midi port.
Its basically 3 arduinoboys stuck together! more info on arduinoboy here.
First find gameboys that work. A couple of years ago i managed to amass over 200 gameboys, sadly im left with the offcuts after backlighting and pro sounding them all. so it was a case of making 3 work again.
The gameboys are mounted with the backs on standoffs behind the panels and the fronts bolted to the front. with all supporting circuitry in and around them.