You foundation piece onto dryer sheets, like you would for muslin or any foundation. I cut my used dryer sheets into squares, sew my strips onto it, then square the block. I started from the center of the dryer sheet & laid down a strip then sewed a strip onto it, pressed, sewed another one down, etc. No need to remove the foundation. So each of the 4 squares in the blocks of my quilt pictured are sewn onto 1 dryer sheet. I hope that makes sense! I think I heard of the technique from The Quilter's Cache.