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A dollar store near where I live sold these little woven plastic tubes called "Pocket Rockets" since if you pushed down on them, and then let go, they'd zing off into the distance.Most people used them as finger traps, since they were shaped like that, and were made of fine plastic threads, so you couldn't just pull them apart. However, because they were plastic, if you pulled hard enough, some fibers would eventually stretch and snap, making it useless.