Sulky makes a wash away stabilizer, it's sticky on one side. You stick it to the back, sew around your shape and when you're done making your quilt, wash it and the stabilizer goes away. You can find it pretty easily at on-line stores, or if you do a google search on wash away stabilizer you'll find it at a variety of on-line stores. I get mine through Amazon. There's another company (Pellon I think) that makes a heavy wash away that I've been using as well. That one is also available on-line (I get that one through Amazon as well).
Rob