An ATtiny85 is hooked up to two limit switches, a PIR sensor and 11 WS2812 LEDs. One switch is triggered by the faucet handle; the other hides under the cupboards for water-less triggering. Lights go on when either switch is hit, and go off 20 s after motion disappears. Thus it triggers when doing dishes, but not when putting dishes away or walking nearby.

I initially tried an IR rangefinder, but I was unable to aim it well enough.

The coding uses WebbotLib, and is quite simeple. Initially I started out doing a purely interrupts/timer based approach... but couldn't fully figure out everything. But it was a great small project for learning some of those lower level fundamentals.