A handier, and tougher version, is available at cooking stores for a couple of bucks. They are made of variously colored nylon that wads up into a tight ball and weigh a few grams each. They are used as shopping bags in Europe. Mesh size is typically about 1/2" square. Laid flat they are about the size of a long gym sock but they expand so you could easily carry a watermelon and still have room on top for more. They are usually strong enough to hold fifty pounds or more.