I use muslim backing for my string blocks which I cut 8 inches. Pick a color for a strip in the middle, black, white, blue, whatever, usually 1 1/2 inches wide. Add any color strips in all sizes, I cut mine between 1-1 1/2 inches wide. If you want to use wider strips, I would make the blocks at least 10 inches square. If I have any fabric 3 or 4 inches wide, I cut them in blocks, then in triangles for the ends of the block. I went to the auto glass place and had them cut a piece of plexiglass 7 1/2 inches square which I used to square up the block from the backside. Other people use paper foundation but after a few of these, I found I hated tearing the paper backing. This is just the way I do mine. Can't post pics cause I don't know how to do that. No method is written in stone. One more thing, they are addicting. Even when I'm supposed to be working on something else, nothing is as soothing to me as sewing string blocks.