(40 / 0.2)^2 = 40,000 LED's * 3 channels = 120,000 channels. On it's own that's a lot of things to control, a lot of things to wire up, a lot of things to solder, a lot of things to buy. Buy you must do all of those things for each LED.
It took me hours to wire up 15 RGB LEDs in strands like Christmas lights. Each lead: cut, strip, tin, clip, align, solder, insulate, test.... 40,000 may take a lifetime.
Edit:
Whoops i misread, but that still comes out to something like 900 LEDs. Not so out there, but we are still talking about weeks or months of work just to wire them together.