I used a treble crochet stitch in this pattern. When you made the bag as you want to larger and ready to making the flap, you must count the stitches and then start the flap. Use the same pattern of the bag, if you want to make bigger flap so, continue some more rounds to the same pattern.
Two colors (orange and skin) worsted yarn 4ply
Main color skin. And 2nd color orange
Crochet Hook 3 mm size
Handle material and buckle