I made ridiculously heavy weather of assembling this trivial circuit on a breadboard this evening. All it takes is:
FSR - two pins, +5V and analog input (1) with pull-down resistor
Membrane - three pins; +5V, GND, analog input (2) with pull-down resistor
All working now, the FSR giving readings of zero to a few hundred on pressure, and the membrane potentiometer with readings on a similar scale based on position. Make a sandwich with them and you have finger pressure/position. With Arduino/Teensy it's fairly straightforward to generate note-on and pitchbend from this, and there are various projects to adapt, like
this one.
Those ribbon connectors are small and delicate though; I'm not going to attempt any more soldering with them, so I've ordered a few of those clinchers, and another ribbon. I'm planning to build a couple of these and sell one to cover the cost of the parts. That's the theory anyway.
Time to start learning OnShape now while I'm waiting for the clinchers...