I used the pad as a pattern. Place pad on fabric (fabric wrong side down)
Next, add 4" all the way around and cut.
Then serge raw edge. No serger, no problem , Zig zag raw edge.
Press up 1/2 " all the way around.
Sew 1/2" seam allowance.Leave a 2" opening along one of the long sides
Using safety pin feed elastic through the casing.Try on ironing board to get the right fit. Sew elastic together and sew up the 2" left.You can cut new batting if needed.Put back on board and enjoy. Take that extra money and treat yourself :)