1. With right sides together, layer blue button print bag body atop red-and-blue stripe bag lining. Sew together along curved edges. If desired, clip 1/8" into seam allowance along curved edges so the finished handle will lie flat (Diagram 3).
2. Turn bag and lining right side out; press.
3. Referring to Diagram 4, match right sides of bag body, then match right sides of bag lining. Sew pairs of side edges together, stitching 1/4" from edges and leaving a 4" opening for turning along one seam. Press seams open or to one side.
4. Rotate bag body and lining to align the seams you just sewed (Diagram 5). Join top and bottom edges, sewing 1/4" from edges. Lightly press sides near bottom and top edges to create creases on bag body and bag lining.
5. To shape a flat bottom for bag body, at one corner match bottom seam and side crease, creating a flattened triangle (Diagram 6). Measure and mark on side crease line 1-1/2" from point of triangle. Draw a 3"-long line across triangle and sew on drawn line. Trim excess fabric, leaving a 1/4" seam allowance. Repeat at opposite corner of bag body.
6. Repeat Step 5 to shape corners on bag lining.
7. Turn bag body and lining right side out through opening. Slip-stitch opening closed. Push lining into bag body to complete reversible purse.