I selected these fabrics for my bag. You need a piece for outside, inside and accent.
Cut for lining and outside a piece 15 inches by width of fabric. Trim off selvages. Cut one 2.5 inch strip for accent full width of fabric.
With right sides together using ¼ inch seam allowance, sew the sides of both outside and lining. In the lining leave an opening for turning on one of the side seams.
Cut 2 pieces 14.5 inches long of accent to make casing. Finish the ends by folding in ¼ inch twice and top stitch. With wrong sides together, press in half lengthwise. Turn outside of bag right side out. Sew a casing to each side of the outside bag along top edge.
With right sides together, place the outside bag inside the lining and pin, sew along the entire top edge.
Turn right side out by pulling unit through the lining opening. Sew the lining closed with a narrow seam.
Mark on outside about 1.5 inches in from corner for grommet. Practice with grommets first!
Thread cording - I used a 2 yard piece for each side.
Hope your little boy enjoys this fun drawstring backpack. Enjoy and Happy Sewing!