Thats quite the interesting cube. 128 control lines to control 512 LEDS.
I see the touch button thing, it looks like they use a photo resistor, and maybe capacitive touch on the other button.
Heres a video of a guy that made circuit boards on glass slides, They use capacitive touch, and you can operate it from back of the glass (not the side with the traces).
I thought it was pretty awesome just because the circuit is on a see through board, but its even cooler as a input device!
I have to salvage some resistors to do some testing, and see if I can figure out the appropriate voltage for each LED.
I did read your webpage about LEDs Grumpy Mike, I assumed as long as you had the right voltage to feed your LED, you dont need to worry about current. As a test, I ran a blue LED on 2 D cells, Im not sure what the forward voltage on the LED is, but my guess is close to 3v. The circuit was simple, 2 batteries and an LED, no current limiting resistor, or any other fancy bits. Based on your webpage, it sounds like I have stressed the LED, but it did not seem weaken the LED any. Im confused, or conflicted, im not sure...
The Shift register way seem a bit more clunky, but thats also kind of appealing. The components will be on display with the cube, so a stack of shift registers, and resisters might be extra cool looking, but not as nice of a way to control the LEDs. I think its kind of interesting how I got 2 totally different responses. Mike, why is the shift register way crap? Im not criticizing, im curious about what is good and what is bad about things. Im also unclear on what you mean by "no as well"