fungus:
retrolefty:
I simple used shift registers that contain built in constant current (sinking) output pins which made the whole brightness thing a no worry situation.RGB cubes are more complicated, they need PWM control for setting the colors...
Depends on how many colors you want to be able to display. Simple on/off to each RGB led terminals should be able to have 7 colors plus all off. It's kind difficult to obtain near infinite colors outputs as well as near constant brightness in the same scanning algorithm I would think and add a lot of complexity to the sketch for the desired pattern/display coding. I think simple on/off controls to the 3000 led elements is the way to go, certainly for ones first attempt.
Lefty