I’ve had this swing for years and the cushions are not original but again, I’ve had them for years. I wanted to give them a makeover. I went on the search for fabric and couldn’t find any that I liked. I finally realized that maybe I could find some sheets at a thrift store that would work. I lucked out and found two twin flat sheets and a pillowcase. I measured the cushions added, 5/8 of an inch, and stitched away. The back has snaps to remove the slipcovers for washing. Good thing since my cats enjoy a good catnap on them.
before
after

The right picture shows the pillowcase that I removed the seams and stitched to the striped fabric and whipped stitched closed.
The twin sheets $2.00 for 2, pillowcase for .25, small pillows $2.00 for 2, and the large bed pillows $6.00 for 2. Total cost $10.25. I love a good thrift store find.