Here, I have crochet conductive yarn with felting yarn and felted it afterwards. It works great as pressure sensor.

Making

Here is the crochet piece before felting. I mixed Schoeller Nm 10/3 conductive yarn with hippy rainbow color felting yarn.

Now it is time to felt. Place the crochet piece on the bowl. Pour hot water, then cool it with cold water. Add soap and rub it really hard with your hand. Repeat these process until the piece starts to get hard and thick in your hand. (You will really feel it)

It shrinks quite a bit after felting. In the picture on the left, bottom piece was same size as the top piece before felting. After felting, it definitely got smaller. If you are making a project that requires exact size, you should consider the shrinkage when you knit. The texture of the piece also changes a lot. It gets much thicker and firmer.