Ever think about painting by consensus? It worked pretty well this fall at Plymouth Church in Seattle. 14 of us painted 16 banners all in one day. Yes, there was a lot of planning beforehand, and that helped it go very smoothly. Now Plymouth has Advent banners adorning their worship space that they have helped design, and have painted themselves.
I gave general color suggestions, and expected that great variations would happen as individuals put themselves into it. People need a frame of reference, but then it's important to back away and let them take off in their own directions. Following are some results: