When you make the original 9-patch, if you keep the centers all the same color, they can create a secondary pattern. Whatever you put on the outer 4 corners of the original 9 patch remain same size squares and the other 4 pieces end up as rectangles.
Here are some pics of ones I did. In both, they were scrappy, but I kept the same colors in the same positions of the original blocks.
http://www.quiltingboard.com/picture...e-t162092.html