I have heard from some people that they used black sashing. I know it's only three blocks, but I kind of like them butted up against each other. I have thought about making some that were half and half. But we shall see what happens when I get more done. Right now I have two of each color. Red, Green, Blue, Yellow, orange, purple, brown, black. I might end up adding a "white" as one of the blocks.
I am linking up to Freshly Pieced WIP Wednesday