Sofa seat cushion
Unpick the seams of seat cushion. Keep the piping, and the square top and bottom. Discard the strip with the zip that wrapped around the middle.
Take one of the large squares of fabric and cut out a 20''/50cm-sided square size plus 1''//2.5 cm seam allowance all round. Put to one side.
Take the calico out of the embroidery ring and cut it to a 10''/25cm square plus 0.5''/1cm seam allowance. Turn under and pin the seam allowance. Press flat. Please don't skip the pressing steps when you make something. It's simply miraculous the great results it gives.