First, I love this quilt! I got my idea from a quilt I had pinned, that links to a no-longer-active Flickr account. I made my own measurements and chose six Kona solids.
Each pinwheel measures 4.25" (each HST is 2.5" finished), and there are two columns of each color, off set with white squares. Each column is sixteen squares/pinwheels high.
I quilted diagonally in both directions through the white squares. The backing fabrics are the leftover solids, plus a strip of Kona Ash, and a purple print that I also used for the binding.
I'm really pleased with the way this one turned out - so fresh and springy!