this tutorial from the Purl Bee blog, but I couldn't make it fit into the correct size requested in the bee. I did the math wrong.
I ended up just playing with the triangles and squares until I got something I liked. In order to get to the correct 12" x 12" size I added a thin border of red and a thicker border of aqua.
Find out more about this online charity bee on the flickr page. I believe Rachel is still looking for members for spin off circles. =]