I'm looking for a way to make a surface touch sensitive. The sensors have to interface with a keyboard encoder to send signals to the computer as keypresses. This is just the way it has to operate. I have capacitive proximity sensors, but I'm thinking they will not be capable of extending their field to an entire (and irregularly shaped) surface. Is there some kind of capacitive switch that can be used with a foil-like material or fabric-like material that could be glued to the inside of an object, thus making the outside touch sensitive?
Usually you would etch the capacitive switches onto a PCB, but with an irregular surface some aluminium foil glued to the back of the surface (with wire from foil to capacitive sensing circuit) should work fine.
The larger the area and the thinner the insulating surface material the better.
A uC like the PIC16F1828 would be good for this application, they have a capacitive sensing peripheral with something like 8 (maybe more) channels.