Prepare Foam and Assemble Cushion
Prepare the Foam
Use heavy-duty spray adhesive to adhere the extra-loft batting 23" squares to the top and bottom of the high-density foam 23" square. Then adhere the extra-loft batting 5x23" rectangles around the sides of the high-density foam 23" square.
Assemble the Cushion
1. Using a 1/2" seam allowance, sew the fleece-lined gusset rectangles together along the short edges; finger-press the seams open.
2. Using a 1/2" seam allowance, sew one long edge of the pieced gusset to the fleece-lined cushion top, clipping the corners as necessary. Repeat to sew the remaining long edge of the pieced gusset to the fleece-lined cushion bottom, leaving one side open, to make the cushion cover. Turn the cushion cover right side out.
3. Insert the batting-covered high-density foam square into the cushion cover. Hand-sew the opening closed. Note: For easier insertion into the cushion cover, wrap the foam square in a large plastic bag, slip it in, and tear off the plastic bag to remove.
4. Flatten the edge along each side seam by pushing the batting-covered foam square away from the seam; pin. To create tufted edges, use a long running stitch and upholstery or carpet thread to hand-sew through both layers of each adjacent side edge, removing the pins as you sew.
5. Using a fabric-marking pen, make matching marks for the placement of five buttons on both sides of the cushion. Cover the buttons with scraps of assorted decorator fabrics. Using upholstery thread and a long needle, hand-sew the buttons on the cushion at each mark to complete the floor cushion.