DIY Force Sensitive Resistor (FSR)

Step 2 Sizing

Use the knife/razor to score your PCB into two plates that mirror each other. I went with approximately one-square-inch squares, but you could do any two shapes so long as there is copper in between.

Cut your foam into the same shape as the plate.

Solder one wire to each plate. You'll want to make sure the solder is going to hold the wire in place, so clean the copper beforehand if necessary and use plenty of solder.