Jemma - A string quilt is made using leftover strips - originally, the odd shaped and uneven strips left from garment sewing.
To mackandblues - not sure if the quilting is visible in this pic, but I just quilted over the strings as if they were any other patchwork (straight line quilting in concentric diamonds). I used a fusible cotton batting (and that will probably be the only fusible batting I ever use) and a pieced cotton backing. The turquoise on front is flannel, however, and between that and the fusible batting and what is for me heavy quilting, the quilt is a little stiff, which is okay, since it was sort of intended as a floor quilt for kids to play on.