Here's what you need: Adult’s chair - 5 yd (4.6 m) fabric 44" to 48" (111.8 to 121.9 cm) wide or 31/2 yd (3.2 m) fabric 54" (137.2 cm) wide for the outer chair - muslin (same amount as for outer cover) -22" (55.9 cm) zipper - 6 cubic ft (1.8 cubic m) polystyrene pellets Child’s chair - 3 yd (2.7 m) fabric 44" to 48" (111.8 to 121.9 cm) wide or 21/2 yd (2.3 m) of fabric 54" (137.2 cm) wide for the outer chair - muslin (same amount as for outer cover) - 18" (45.7 cm) zipper - 4 cubic ft (1.2 cubic m) polystyrene pellets
To make either size chair, place tracing paper over a 1" (2.5 cm) grid, and draw the pattern using the illustration as a guide.
For the chair bottom pattern, fold a piece of tracing paper in half. Mark the center of the folded edge. Measuring from the center, draw an arc with a 12" (30.5 cm) radius for an adult’s chair or a 10" (25.5 cm) radius for a child’s chair. Unfold the paper; mark a line 1/2" (1.3 cm) from the fold. Cut on the marked line. Discard the smaller section of the circle and use the larger section for cutting.
Use the side panel pattern to cut six side panels from the outer fabric and six from muslin. Use the bottom pattern to cut two pieces from the outer fabric and two from muslin. From both the fabric and muslin, cut one circle with a 51/2" (14 cm) radius for the top of an adult chair or a 41/2" (11.3 cm) radius for the top of a child’s chair.
Pin the straight edges of the chair bottom pieces together with right sides facing. Machine-baste the edges together, using a 1/2" (1.3 cm) seam allowance and stitching 1" (2.5 cm) at each end of the seam with a regular stitch length.
Press the seam open. Center the zipper right side down over the seam allowances with the zipper teeth on the seam line. Glue-baste or use basting tape to secure the zipper tapes. Stitch down each side of the zipper 1/4" (6 mm) from the zipper teeth. Remove the basting stitches.
With right sides facing, use a 1/2" (1.3 cm) seam allowance and sew the side panels together, leaving the last seam unstitched. Press the seam allowances to one side, pressing all in the same direction. On the right side, topstitch 3/8" (1 cm) from the seams, securing the seam allowances. Sew the remaining seam, press, and topstitch.
Staystitch the upper edge of the chair a scant 1/2" (1.3 cm) from the edge. Clip the seam allowance up to (but not into) the stitching at 1/2" (1.3 cm) intervals.
Divide the outer edge of the top circle into six equal parts and mark with pins. With right sides facing, pin the top circle to the top of the chair, matching the pin marks on the top to the seams on the chair. Sew the top in place, using a 1/2" (1.3 cm) seam allowance. Press the seam allowances toward the sides. Topstitch 3/8" (1 cm) from the top seam to secure the seam allowances.
Repeat steps 8 and 9 to attach and topstitch the bottom of the bean bag, leaving the zipper partially open during assembly to turn the bean bag right-side out.
Repeat steps 5 through 10 to assemble the muslin lining. Insert the lining into the outer cover. Fill the bag with polystyrene pellets. Close the zippers.
This sewing tutorial is excerpted with permission from <a href="http://amzn.to/1hLUVHM">"The Complete Photo Guide to Slipcovers, Pillows, and Bedding"</a> by Karen Erickson and Carol Zentgraf and published by Creative Publishing international.