I'm a procrastanator, so as soon as I get one, I try to do my part and pass it on. This one is to move on March 15, I'm way ahead.
The size I got was 27.5" square, divisible by 3 x 3 x 3. Then noticed the center is a basic 9 patch. So it has 3" 9 patches with spacers. The corners are basically 1/2 square triangles, so I repeated it in the corners. My style shows in the light WOCream for a higher value contrast.
Measuring and remeasuring was important. If 1/16" error is repeated 16 times, it's off by 1". I've gotten sloppy on 1/4" seam.
Hope you like it.