I also have used the foam fabric used as head-liner for cars. Found it at Joanne fabrics, or upholstery stores. Works beautifuly for the larger bags. You can quilt it to the outer fabric or, as I do it, make it as a "second" bag, tack it to the outer fabric at the seams, then line as pattern instructions. I also use a medium weight interfacing on every piece of lining fabric. Pockets mandatory, I hate baggy pockets.