I was thinking of making an array of capacitive keys, someone would have a wiring diagram?
Hardly needs a diagram (and I am not so good at drawing them to my personal satisfaction at this point), but each of the "sense" pins has a capacitor of something like 10 nF ("103") from that pin to the touch point (the capacitor is to prevent DC voltages getting to the Arduino pin; if your sense electrodes are already adequately insulated; you do not need this) and a 4M7 (green-yellow-green-gold or green-yellow-black-yellow-gold) connected from that sense pin back to the single common "drive" pin.
It appears to be a common recommendation to put something like a 47pF capacitor from each touch point to ground on the basis that if the capacitance to be sensed is too
low, it becomes difficult to write code that implements the timing loop to be fast enough to measure it at all. The code should not