I have some leftover batiks in my stash from a quilt I made for a friend. They're not my colors or my particular taste. I thought I'd make a set of placemats for my friend as well by using the tube quilting method. Well, I made one and used 2.5 in. strips on the side to make it rectangular, but it doesn't seem quite large enough (16"x12"). What's "normal" or at least practical for placemat size? Thanks!