For the "Rainbow Cheapskate" challenge.
My idea was to use primary colors to make up the rainbow's hues, and the scene here was my idea for the context of the rainbow. The rainbow itself is magical coming from that pot of gold, so I gave it an extra glow.
This will also make a good avatar for the Red vs. Blue war, where both colors and a neutral are all reprsented at once.
EDIT: Brightened the blue & red. Hopefully this helps readability.
EDIT 2: Attempted to make the scene a bit more clear as well.