Dynamically varying FSR pressure can be mapped to the following string parameters: nail/pick attack shape, timbre and amplitude (pink noise/white noise); string-note amplitude, timbre and resonance. I have also implemented aftertouch vibrato. Consumer FSRs are very flat, very plastic, and don't offer much haptic feedback; aftertouch will work 'better' given different materials - hence a predicted DIY approach to the FSR. Here you can see the variation in fingertip contact area and force, which causes the change in resistance:
Up next is a detailed demonstration of the instrument environment in use.