This is a 4-output resistive touch controller I developed originally based on this video here.
It works by passing 12V through your finger (you'll be fine), into some capacitors, dropping the voltage, and buffering it. Pretty simple! As you can see in the pictures I put masking tape behind the touch sensors to keep them from the grounded panel. And the holes were drilled bigger than the threads, again to avoid contact.
Since making this module I've upgraded from using sharpie to toner transfer for etching, so I decided to revisit this layout and update it. For us. The new layout is about half the size and way less ugly!
These are at 600dpi. And here's the schematic. Take note of the 100ks from V+ to the touchpads--they're not on the PCB.
Out with the old, in with the new.