Candle consists of three main boards that are stacked in a similar way as the good old Arduino Uno shield boards. From bottom to top, the three boards are as follows:

A charging board is directly soldered onto the super capacitor. It provides a USB-C connection that is used to power the charging circuit. The STUSB4500 IC manages USB-C power delivery setup. The BQ24640 is used to quick-charge the super capacitor to 2.7V with a constant current of about 3A. 

An 8MHz ATmega328P-based Arduino board with the high efficiency boost converter MAX17224 to provide a 3.3V constant system voltage down to about 0.5V super capacitor voltage. Low input voltage operation is important to capture as much charge as possible from the super capacitor. In practice, LEDs can be operated down to about 1V.

The top board contains three RGB LEDs with a matrix drive scheme, a linear poti, and a button for user input. 

Candles make a nice decoration for the Christmas tree or stand alone with a little bit of Selenite crystal.