Really nice project ! How did the conductivity of the buttons work out ? - I noticed that you used a slightly different pattern for your "zigzags" on the PCB. (Did you try silver? - From what I've heard silver continues to conduct after oxidation.) I was also wondering, how this project continued. Did you manage to build a case ? Other people who did similar projects, also designed custom silicone button pads. - Did you ? You don't happen to have the coordinates of a supplier of affordable custom silicone buttons, do you ? :) How many PCB layers did you need ?