The game looks awesome and the idea is really good.
It's a bit hard to tell what to say as the critic but maybe i'm just too lazy to read and just answer randomly haha.
One thing i noticed is that you can't switch paint with the 1, 2 and 3 keys, it think that would have been much more useful, although it would be less realistic as you are not dipping the finger on the paint.
This is truly a piece of art.