a few years ago I bought a flexible bottle of water at a quickie mart in Calif. the quality of plastic was similar to the Evernew flexible canteens..only the shape was like a platypus.(sort of peanut shape when filled with water) I took and cut the bottom 5-6" off (about at the waist). without content the cup lays flat, but when I'm ready to use it I can, with one hand squeeze the two welded seams together and the cut line, opens to form a large cup shape (sort of like an old school coin purse). about four scoops and a one liter dirty canteen is filled. lays flat and I rubber band it to my sawyer mini, and weighs next to nothing.