To make a replacement canvas for an outdoor swing, remove the old canvas from the swing, measure the canvas, lay a cotton fabric on a flat surface, glue a tablecloth on the fabric, and place the newly-made canvas on top of the frame. Lay a tarp over the frame.
Clean off the frame, measure the length and width of the old canvas with a tape measure, add 6 inches to the length, set a closely woven cotton fabric and waterproof tablecloth on the ground, and glue the materials with a liquid adhesive. Make sure the cotton fabric faces down and the tablecloth faces up. The lengths of the fabrics must be the same, but the width of the tablecloth should be 2 inches smaller. Level the materials out with a heavy, flat block, and let the adhesive dry.
Place the glued fabrics over the swing's top frame, fold the extra fabric under the bar all along the top frame of the swing, mark on the underside where the two fabrics join, and using liquid adhesive and hook and loop closure system, fix the edges of the fastened materials to the markings. Lay a tarp with the same measurements as the swing's frame over the top frame, and via grommets, fasten the tarp to the frame's bar with zip ties.