Cut the pieces to size. You need 2 pieces of your main fabric and 2 of your duck cloth measuring 9X13 inches. For the strap cut a piece 3X13 inches and the for the inner section 2 pieces of duck cloth 9 by whatever is left (probably about 17 inches).

With right sides together sew the long sides of the 9X13 pieces to the matching piece with a 1/2 inch seam allowance. Now you should have 2 tubes

Open the seam and iron. Turn the outer fabric right side out and slide it around the duck cloth piece. Fold the top edges under 1 inch and press.

Make the strap by folding the strap piece in half lengthwise and sew one long edge and one short edge. Turn right side out and iron.

Tuck the unfinished edge between the folded edges of the tubes you made at one of the seams.

Sew around the top edge of the tube making sure to catch the strap. Now you should have one tube with a finished top and raw edges at the bottom. Set that aside.

Take the 9X 17 inch pieces and sew the long edges with a 3/4 inch seam allowance.

Fold the top edge under in 1/2 increments until it’s about the same size as the other piece you made. (It just needs to be a little shorter so it can sit inside without showing).

With the first tube (double layer/outside) piece turned wrong side out (so the pretty pieces are on the inside facing eachother) tuck the first tube inside the tube you just made.

Sew across the bottom catching 6 all layers.

Turn right side out and you’re all set. Use a button or saftey pin to adjust the strap to the desired length to sit around your gear shifter and tuck in a doggie or diaper trash bag around the edges.