Adafruit Soft Potentiometer Kit from Plug&Wear [ADA2273]
This soft potentiometer is an interesting way to add an adjustable resistor / slide potentiometer to your wearable. You can use it to adjust the brightness of an LED, or as a sensor input to your Flora or Gemma. When the ring slides up and down the ribbon, the resistance from the end of the ribbon to ring will vary from ~100 ohms to about 8Kohm.
To use as a voltage-output potentiometer, connect one end to ground and the other end to 3.3V or so, then measure the voltage on the ring in reference to ground. For an adjustable resistor, connect to one end of the ribbon and the ring, let the other end hang disconnected.
The kit includes 50cm of specially-woven conductive ribbon and a stainless steel metal ring.