1. Mark top center of bag side edge. Fold 2" on both sides of center mark together to make an inverted box pleat (Diagram 17). Baste in place. Repeat to make pleat at opposite bag side.
2. Mark lining top edge 2-1/4" from a seam in both directions. Fold lining edge 1" at each mark to make a box pleat (Diagram 18). Baste in place. Repeat to make a box pleat at opposite side of lining.
3. Insert lining into bag body with wrong sides together. Align folded top edges and nest pleats.
4. Topstitch bag body and lining together 1/8" and 1/4" from top edge to complete bag.