One way to defend your personal space is to carry a halberd while wearing a Strawberry Shortcake t-shirt but no pants. Not everyone, oddly enough, is comfortable with this approach. For them, Zac Ong may have a solution. His project, entitled Repel, features a rotating shoulder-mounted laser. When it detects that people have entered his personal space, it alerts him with LEDs and buttons that blink and spin with increasing speed as the intruder approaches.
Link -via Gizmodo