Before start reading, I would like to say this "LED cube" did not controlled by microcontroller, it just a "LED cube"-like lighting...
This LED cube using 27 LED which is self changing color, they all solder in parallel and the power supply is 9V battery with a AMS1117-5.0V 5V regulator.
I did this quite a long time, it is cheap, beautiful, easy to make, and I think someone would like this battery power lighting or even as a lantern.
So, please watch the video.
AMS1117-5.0V 5V regulator.