When you're biking, it's important to signal the other vehicles
on the road—cars and bikes alike—when you're going to turn,
change lanes, or make any other movements that may put you in
harm's way. Unfortunately, few people know hand signals anymore,
so Instructables user CTY1995 decided to make his own wearable
turn signals that he could put on his arms and turn on by
lifting his arm up from his side. The beauty of these turn
signals is that they use a mercury tilt switch and some
electroluminescent (EL) panels that light up to show big bright
arrows every time he lifts up the arm that corresponds with the
direction he wants to move. Combined with some Velcro and
armbands, the panels make a comfortable, wearable gadget that
can make your bike ride much safer. Best of all, the tilt switch
is sensitive enough that you don't have to start waving your arm
wildly in the air to turn it on—just a slight lift will do the
trick, and everyone around you will know where you're going. If
you want to make your own, check