Cut two piece of duct tape, about 4-inches long. Cut each strip in half so you end up with 4 pieces that are each about 4" x 1".
Lay one of the piece of tape, sticky side up, on your work surface. Lay one edge of the packing tape window along one of the long edges of the tape so it overlaps the tape by about a 1/4 of an inch. Fold up the other long side of the tape onto the packing tape window, just 1/4 of an inch. Trim an extra tape flush with the edges of the packing tape window. This will finish one edge.
Repeat this step with the other 3 edges of the packing tape window. Not only does this give your window a nice, finished look, it also makes it a little bigger!
You are now ready to attach the I.D. window pocket to the wallet...