Vintage Synth Repair

Hi Alan
I should have mentioned, although I'm sure you don't need this info, that the foil should have a resister going to GND

         ___________________________________
  Gnd  8======================================8 5V
  Gnd -^v^v-8______________________________8| Out

 
Using a PCB (you might like to gold plate it 8) ) you could have a number of tracks under the rubber (all grounded and a separate feed to the ADC).
You would be able to detect guitar type pitch bend although it would be quantized.
You could use a piezo strip attached at one end of the rubber to detect strain and this would make it analog.

I used an ATMEL 8 bit controller that had a muxed ADC inbuilt as well as a Midiable UART and Flash memory to store settings.

All the best
Royce