A lengthy pin potentiometer. Something like a slug on the back of your hand. Filled with polenta. You poke the sharp pin through layers of conductive fabrics (and the polenta), one is highly conductive the other has lots of resistance. The pin is conductive and makes an electrical connection from the conductive wiper layer to the resistive track layer, allowing electrons to flow and divide the voltage between VCC(+) and GND(-).

Photos >> https://www.flickr.com/photos/plusea/albums/72157710659929946

NO PIN:
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
A0___________________________________ —> conductive wiper layer
o o o o o o o o o o o o o o o o o o o —> isolation layer
(+)VCC–vvvvvvvvvvvvvvvvvvvvv–GND(-) —> resistive track layer
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *

WITH PIN:
>ignore the .dots.<
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
……………. PIN
…………….. _
…………….. |
…………….. |
A0________________|__________________ —> conductive wiper layer
o o o o o o o o o | o o o o o o o o o —> isolation layer
(+)VCC–vvvvvvvvvv|vvvvvvvvvv–GND(-) —> resistive track layer
…………….. |
…………….. |
…………….. v
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *