My replacement trigger board for the PS4 controller only does digital (on/off). The original has a force sensing resistor built in, allowing for analog readings. I figured it was a long shot, but I wanted to play with some ideas for putting in an analog sensor.
Using an FSR didn't quite work, mine where all to big. I played with some based custom sensors made of tape, aluminum and velostat like film but the resistance was off the charts. Then I had the idea of attaching the plastic right to the board - still too much resistance. But finally I tried just jamming some conductive foam between the membarane and the board, and low and behold it worked! Not that it's a very sustainable solution, but its a good proof of concept.