I love this idea! Denim weaving I can imagine how great this would look with other things (not just a purse) such as a quilt or a jacket back maybe even a chair cover O the possibilities are working in my head now.
Perfect hem line - draw a line on card stock, 1 inch in from edge of card stock. Place the card stock on fabric, with line parallel to fabric edge. Fold fabric over card stock, aligning fabric edge with line; press with an iron.