I have made several t-shirt quilts fior my granddaughters with t-shirt/clothing designs as small as 3 inches to ones that are the entire block. Some of my blocks may contain two or three designs from different t-shirts. I put borders around each design to complement each individual t-shirt. My finished block size depends on the size of the largest t-shirt design used, usually 15 or 16 inches. I think the finished quilt has a lot more character and interest that the ones with the t-shirts all the same size. It's fun to look at the finished quilt and discover all the different designs.