I am always looking for inexpensive items to help my photography. I was at the grocery store yesterday and found a plastic insulated lunch bag someone had misplaced in school supplies. Upon looking at it at home, it is indeed a perfect fit for either my Calumet roll film back or five 4x5 holders with good room, six in a pinch. Seven in a real pinch. It has a substantial velcro belt loop in the back and a top handle for attaching to a back pack or carrying. It costs $5.99. Worst case scenario, it will carry a small water bottle or two and some lunch. It is made by Outer Circle Products and is called an Arctic Zone Insulated Lunch Bag Collapsible. It has a label RLU54000-02 and a bar code number 16497 54000. This particular one happens to be purple...don't know about other colors. A length of string tied to the top or back could hold it on the tripod during use for easy access....I think the next time I go shopping I will try to find a couple more.