Congratulations! Very nice concept!
The miniAtmegatron is delivered with headers that are soldered at the top face of the PCB. Would it be possible that I replace some of them with stackable headers? I mean, is there some solderpad foreseen at the bottom of the board so that I can solder the stackable header? These headers may maybe hamper a bit the accessibility of buttons and pots, but it would allow me to easily use jump wires to further experiment/extend the design.