I bought some muslin preprinted with the lines for the log cabin blocks. Making these was really easy since the foundation markings meant I could use scraps of various sizes and still be sure they would be right after cutting. I used this for a quilt guild members choice block exchange and gave each person the square of muslin and the center block and told them darks on the one side and lights on the other. I got a lot of variety in the fabrics as a result.