Make you pattern as follows: cut a large rectangle of 33" by 18" then 2 small rectangles of 14" by 5". Looking at the long sides of the large rectangle, find their middle. Looking at one of the short sides of the small rectangles, find the middle. Match this middle to the middle of the large rectangle on one side and tape together. Repeat for the other small rectangle and the other side of the large rectangle.

Cut 2 pieces of vinyl fabric using this pattern.

Cut the strips of the thick fabric for handles. At this point you might be wondering why can't you use vinyl. Well, you can but vinyl is not stretchable and doesn't fold nicely. So when the handles fold, they create lots of creases. Which in time will damage the vinyl, especially since handles get a lot of use.

Now that your fabrics are ready, find the other middle of the small rectangles and fold rectangles in half. Use clips to keep in place. Take your fabrics to the sewing machine and top stitch along the middle line and stop 2" before hitting the bag. Repeat for all small rectangles.

With fabric wrong side out, clip small rectangles to the bag then sew down with 1/4" allowance. Do not backstitch!

If you like to, now you can also box the corners as indicated here. I chose to skip this part since the bottoms are sturdy enough thanks to the double layers of heavy vinyl fabric.

Repeat for both bags then turn only one of them right side out. Do this as quickly as possible to avoid permanent creasing, pushing corners out with your fingers.

Measure about 1" down the top of each bag and fold the top inside (towards the wrong side of the fabric). Clip to keep in place and finger press along the top.

Make the corded bag handles as indicated here.

Remove the clips on both bags. Then take the bag with the wrong side out and slide it inside the bag with the right side out. Clip together at the top, making sure the seams and sides are matching perfectly.

Measure about 4" from each side of the bag and slide the handles in, between the 2 bags, then clip.

Take the bag to the sewing machine and sew down along the top with 1/4" allowance. Sew slow over the bulky seams at the sides.