Classroom warfare is tough. You have teachers hounding your stash, cute girls to impress, punk kids coming up with punkier ways to punk you—basically a lot to worry about. That's why you need this rubberband shooting ruler.

Designed by Sebastian Bergne, it looks like a regular ruler so you can avoid confiscation but delivers pain harder than the ol' wind 'em up with your finger method. You'll be king of the class. [Buy Sebastian Bergne via Dezeen]