Lighting a massive (6'x4') canvas using RGB LEDs

Um, yeah, sorry about that, that was meant for another topic. Guess I didn't copy the link I wanted.
Glad you able to find some.

What about backlighting it instead?

Please explain, what is the purpose of the different colored lights on the screen with handpainting at the same time?

Post a link to the LEDs you found. Am sure there are multiple suppliers in the UK to be able to find something workable.