Fold the fabric in half, bringing the 18-inch sides together. Sew along the edge of the 18-inch sides with a sewing machine. Iron the seam flat.
Place the zipper face down and in the center of the 18-inch side on top of the seam. You should have 3 inches on each side of the zipper. Sew the zipper in place with a sewing machine. Use a seam ripper to remove the stitching over the opening of the zipper.
Sew along the 3 inches before and after the zipper to reinforce the seam.
Fold the fabric so that the zipper is in the middle of the front of the pouch. Iron the pouch flat.
Sew along the right and left sides of the pouch with a sewing machine.
Open the zipper and turn the pouch inside out.
Pin the pouch to the back side of the webbing belt near the buckle. Sew along the left and right sides of the pouch with a sewing machine.
