You can use almost anything to make a pillow form....calico...ugly fabric...I have even used old rayon scarves that were to ratty to wear. Polyfil type stuffing sold in craft stores is probably the easiest to get....but I have pulled old bed pillows apart...as long as the stuffing still has some "spring" I'll use it. Also if you stitch around the seam twice...it is really robust, so you can stuff it as firmly as you like. Your bargello is beautiful...if it were mine I'd quilt it then do a simple zippered backing...easy on and off for a wash.