After working the entire design, dampen and block the piece so that the design area is squared and measures 13x13-inches.
After blocking (be sure the piece is thoroughly dry), trim canvas to within 1/2 inches of the stitching. Attach piping using the sewing thread (a zipper foot is perfect for attaching piping), overlapping the ends of the piping. Stitch the completed front to backing fabric, right sides facing, along all 4 sides leaving a 10-inch opening along the bottom edge for turning. Clip corners to, but not through, the stitching line.
Turn the pillow covering right side out and stuff. Hand stitch the turning opening closed to complete the project.