Cut pieces in the following order.
From blue print, cut:
2 4-x-34-1/2-inch strips
From blue-and-green print, cut:
2 14-1/2-x-16-1/2-inch rectangles
From green print, cut:
2 14-1/2-x-20-1/2-inch rectangles
6. Layer bag units' with right sides together; pin. Pin loose portion of straps in place to prevent catching them in stitching. Join units around all edges, leaving a 5-inch opening at top center for turning (Diagram 3). Press seams open.
7. To shape flat bottom for bag, at one corner match bottom seam line to side seam line, creating a flattened triangle (Diagram 4). Measuring 2 inches from point of triangle, draw a 4-inch-long line across triangle. Sew on drawn line. Trim excess fabric. Repeat with remaining bottom corner of bag, and both corners of green print lining.
8. Turn bag right side out through opening and finger-press seams. Slip-stitch lining opening closed. Insert lining into bag.