I used quilter's cotton which I would recommend over broadcloth because it has a heavier weight. Once the t-shirts were fused to the interfacing they were quite heavy and some of my sashing strips rippled because of the difference in weight. I can only imagine that it would be even more of an issue with a lighter weight fabric. Or you might apply interfacing to the sashing strips too???? Just a thought! Good luck and I can't wait to see it when you are done.