I made one with 8.5" squares because that was the size of the horse heads.See--
http://www.quiltingboard.com/t-148348-1.htm Unfortunately, the colors are way off in the photo, but you can get some idea of size.
The more I think about your idea, the more I would like to try it on a kid's quilt. Just pick out nine fun fabrics and that would be one quick quilt-the Super-sized D9P (SSD9P)