Doing a mandala sounds like a great project-they are so BEAUTIFUL! And you have all sorts of room for creativity.
I've got a mandala book on my Amazon wishlist, but haven't bought it yet.
I'll be watching to see how your project progresses! Spacing the pieces is an interesting concept for sure.
Wendy
P.S. WOW, some of those coloring pages would make great quilting designs as well as piecing designs!