a box that hides Bitcoins for 18 years.
Based on a esp32 - az-Delivery Board and an adafruit real time clock. The RTC is connectet to 2x AA Lithium Battery (shelf time 20years). The Battery as a capactiy ~2300mah, current of rtc 150 nA --> 2300/0,00015=15.333.333h ->theoretically it would run 1.750 years. So 20 years should be sure possible. (self discharge) The drift is around 2s per day. So after 18 years there should be a maximum of around 4h error.
after reaching the 18. birthday date the box can be powered ofer usb. the esp32 check the date from the RTC and provides a Wifi-AP with Captive Portal -> it will redirectet to a website where the BTC and PrivateKey are shown.
If the box earlier pluged in, the esp32 wifi will show something like "be cool" :)
You find the arduino Sketch and the libraries here.