Summer is here and so is frequent excursions to the nearby lake. I wanted a bag to put the towel, swimsuit and maybe a book into and this is what I came up with.
I used an A4paper for measuring. This does not mean the bag is A4sized, it is a bit bigger.
In the picture the bag is loaded with a towel, a swimsuit, a book and a 1,5 l bottle. Still plenty of room.
Instructions here. And yes, this my own design.