...One button is to change from AM or PM, and the other is to turn on one of the LEDs representing the current choice for 5 seconds. The unit then goes to sleep, and the LEDs are off. It is powered by an 18650 and I put it all in a medicine bottle.
A description of it's construction, as simple as it is, is at an instructable here: https://www.instructables.com/id/Did-We-Feed-the-Pets/
Current draw:
Awake: 5 mA
Sleeping: 0.13 uA (!)