Don’t you wanna watch me spill? Alerting when a container is nearly full of liquid.

Arduino C++ Contrivances The Diary of Lupin Pooter
There may come a time when you need to know if a container being filled with liquid that flows at a slow, variable rate is nearly full so that you can empty the contents or do something else with the stuff inside. Such a need recently arose here and I put something together using an Arduino (Cloneduino) Nano, a couple of non-contact capacitive water level sensors, a WS2812 LED breakout board, and a piezo buzzer.