Here's a mini tut with drawings! I might make a longer one with pictures in a few days because I'm going to make another one for me (the first one I made did not turn out as I wanted).
What you need: a beach towel, and another towel. I used one that is like.. half the size of a regular towel.
Cut it up! I don't know the measurements, so I guess just cut it however big you want your bag to be
1 - The side of the bag.
2&3 - The straps.
(The other, lighter part, is the little design part they put on each end of towels... I basically redrew all of the steps I did for the bag I posted, so I even posted how I did not use that part for the straps... because I wanted both of the straps to match.)
Place the side piece in the center top of the beach towel and sew where the red squiggly line is. There are no wrong or right sides of the bag, since it's essentially reversible.
Place the handles where you want them, two on the beach towel side, two on the smaller towel side, obviously, and sew in place.
Ta da, you're finished! Fold up and you're ready to hit the beach!
To fold the bag up, flip it over to the back side, and fold the sides over, and start folding it back up towards the purse part. Once you're "behind" the purse part, flip it inside out, much like you would a Popple. Maybe I'll take pictures of this process as well.. I'm not so good at explaining it haha.