Fold a black-and-white polka dot 3-1/2x38-1/2" strip in half, wrong side inside (Diagram 1). Press, then unfold. Fold long edges to meet in center; press again. Refold in half and press. Topstitch 1/8" from each long edge to make a strap. Repeat with remaining black-and-white polka dot strip to make a second strap.