How complicated a circuit would you need for this to work? A simple, hollow cube, each side with about 25 LEDS on it (looking a little like a... Show More
Most Helpful Opinion
You can use software or hardware (like almost any other circuit).
Unfortunately I've forgotten most of my electronics.
You'll be working with some kind of shift register. Look up things like Johnson counters, ring counters, sequential logic, etc. You might even check combinational logic for a semi-random affect.
You will need some sort of clock, like an oscillator, frequency generator, or something simple like a "triple nickle" (search 555 timer).
You can use simple RC networks for short time periods like 15 minutes. For long term timing up to 4-5 hours might be a little trickier. I've forgotten most of this stuff and can't think of anything off the top of my head for long term timing other than a processor or a counter combined with a 555.