Take your map and clear vinyl. Iron the vinyl to the front of the map. Iron the interfacing to the back of the map to strengthen it.
Sew lining to the back side of the map.
I straight stitched it to the map on all four sides, turning over the top and bottom to give it a more finished edge on the top and bottom.
Fold the map over so that the back is about 6 inches longer than the top (this longer part will be the front flap).
Sew the seam on the side and push the bottom corners under to create a hard rectangular bottom. Cut a piece of cardboard to match the size of the rectangle. Cover it with fabric, and glue to the inside bottom of the bag.
Fold the overlapping flap over the front. Glue the soft side of Velcro, one piece to each inside corner of the flap. Figure out the corresponding points on the body of the purse and glue the bristle-y side of the Velcro to two points on the body.
Add a hole on corresponding sides of the purse and set a grommet in each. Add a ball chain that is the right length for you and add a ball to the end of each side of the chain inside the purse. Add one more grommet to the front of the flap right in the middle and pull your keychain chain through. Put the keychain ring on the back side of the chain so it doesn’t pull through the hole. Voila!