Barepaint +LED
https://www.bareconductive.com/make/how-to-use-electric-paint-with-leds/?utm_source=leds_tw&utm_medium=ep_leds_tw&utm_campaign=use_ep_and_leds
Barepaint +resistance with multimeter
https://www.bareconductive.com/make/use-a-multimeter-with-electric-paint/