I did find this stripe that just looked like a swing cushion, it was 50% off, so I got it.
Rummaged around in the basement and came up with one of those foam egg crate things, looks like a good cushion filler. Several folks have stuff stored in our basement, hopefully it was actually something that belonged to me! Oh well, too late now!
Cut the egg crate twice as big as the needed pad size, fold it in half so the smooth side is on top and bottom and the egg crate points fit together.
Cutting the fabric - For the top of the cushion cover, cut fabric the length of swing plus half of thickness of pad on each end plus a seam allowance. For the bottom, cut the same size as the top plus about 8 inches for overlap.
Cut the bottom piece in half, hem one edge of each half.
Lay out the piece for the top, right side up. Lay out the pieces for the bottom on top of this, right side down, overlapping the hemmed edges.
Sew around the entire rectangle, no need to keep a place open for turning.
Corners: While still inside out, pull fabric out at corners and match the two seams making a point. Measure down from the point half the thickness of your pad, and sew across in a straight seam (at right angle to the other seams). My pad is 2" thick, so I measured down 1" from the point and stitched across where the horizontal pin is in the above picture. Trim corner.
Turn right side out, insert your foam pad, see how on the back the two sides overlap.
Voila! Swing cushion.
Quick and easy, no zipper, easy to remove for washing, reuse/recycle old foam.
Product tester Maggie gives it a thumbs up (or paw up, or maybe just a yawn)
Added perk - I got to use the pin cushion made my granddaughter Madison!