Fold your material in half and measure 12 inches by 16 inches. Cut the material where you have measured and separate the two pieces.
Fold the top of each piece down approximately 1 1/2 inches and pin it down. Iron the folded section and sew the flap down with a straight seam leaving the ends open.
Place the right sides of the fabric facing each other and pin them together. Sew a straight seam 1/2 inch from the edge all the way around the two sides at the bottom. Start the new seam at the bottom of the folded seam at the top and end just underneath the folded seam on the other side. Flip the bag right side out again.
Cut two 12-inch sections of cording and attach a safety pin to the end of each. Thread one section of cording through each side of the folded sections on the top of the bag using the safety pin as a guide to pull it along to the other side. Remove the safety pins and knot each end of the cording to keep it from slipping back through the bag.
Place a pair of shoes in the bag and pull on each side of the cording to cinch the opening closed. Tie a knot at the top to secure it.