[lrasinen]

Also made one for this year. My particular challenge is that we need a heavy-duty tree stand to account for feline perturbations. This means the water capacity is pitiful (0.5 litres, perhaps). Also there's not a lot of room for float switches.

My design has an optical water level sensor and a cheap peristaltic pump, plus an ESP8266 for sanity ("if on for more than 5 mins, sound the alarm").

Sensor: https://a.aliexpress.com/_mtzF1L6 Pump: https://a.aliexpress.com/_mrGsfVO