1. Mark top center of bag side edge. Fold 2" on both sides of center mark together to make an inverted box pleat (Diagram 15). Baste in place. Repeat to make pleat at opposite bag side.
2. Mark lining top edge 2-1/4" from seam in both directions. Fold lining edge 1" at each mark to make a box pleat (Diagram 16). Baste in place. Repeat to make a box pleat at opposite side edge of lining.
3. Insert lining into bag with wrong sides together. Align folded top edges and nest pleats.
4. Topstitch bag and lining together 1/8" and 1/4" from top edge to complete bag.