Place a piece of wax paper over the seat and trace the exact seat shape onto the paper.
Place the foam over the seat and trace the shape around the underside of the foam. Cut the shape from the foam and set aside.
Set the paper on a flat surface, measure 4 inches outward from each corner of the traced shape and mark the spots to create a guide to enlarge the pattern.
Use the marks to trace the entire shape four inches bigger on the paper to allow room for a 1-inch seam and 3-inch foam form.
Cut the enlarged shape from the paper.
Lay the fabric on the flat surface and place the paper cushion pattern over the fabric. Trace the pattern on the fabric two times and cut out each shape.
Place the first shape on a flat surface, right side up, and lay the second shape over the first, right side down, and line up the edges of the fabric.
Insert a pin 1 inch from the edge of the fabric, positioning it vertical to the edge. Repeat the process around the perimeter of the layered fabric shapes to secure them together and create a guide for the 1-inch seam.
Sew three sides of the cushion together with a sewing machine. Remove the pins from the fabric. Turn the fabric right-side-out and stuff the foam form into the cushion.
Fold the edges on the remaining open side of the cushion inward 1-inch. Slide a pin into the open seam, positioning the pin vertically to hold the fold. Thread a needle and hand stitch the seam closed.
Repeat the entire process to create additional breakfast nook cushions for the set.