My youngest and I recently attended a program about survival. During the program, the man presenting the information showed us the bag he made when he was a young boy that he still used every time he was out doing wilderness training. He said none of the expensive bags he purchased over the years could stand up anything compared to the one he made himself.
Inspired by his simple design, we decided to create one ourselves. We lined ours with a muslin fabric and stitched the entire thing together with z stitches. It is durable and strong. I'm not sure yet what specifically it will be used for, but it was quick and fun to put together.