When I want to substitute fabric I get into my stash of scrapbooking paper. I thought I wanted to scrapbook, bought a ton of supplies and then decided scrapbooking wasn't going to be my thing. I use the paper to help determine value and color selection. I go thru my fabric stash to find which ones I have the correct yardage amounts - then I look for scrapbooking paper in similar colors. I cut the block pieces from the paper, put it all together, play around a lot and then make the decisions for the fabric. I still make a sample block from fabric just to be sure I like my choices. I didn't think to post this tip before now, I hope it helps all of you that are hording a stash of scrapbooking paper and don't know what to do with it. :D