Eruv strings are often inspected on Thursdays. If you find one-- say, on a Friday that "should be" strung between two of your local municipal signpoles or stoplights, but you see the string is broken, perhaps you can "weld" it together with this marvelous new technology-- a Green Laser pocket laser! In the spirit of helpfulness, it's worth a try. Your public utility, Chabad Lubavitchers and Hasidic rebbes and gedolim pre-thank you!