This week Joerg invited some students from the Technical University of Munich to create general mayhem with him via a steel axe. But an axe by itself isn't menacing/relevant enough. It obviously has to double as a slingshot. And it does! The handle of the axe is hollow . . .

The device houses four aluminum tubes, a magnesium firestarter and three steel tipped bolts. Because the axe is meant to be a survival tool (by the way the axe is meant to be a survival tool) one of the bolts has an active carbon water filter and can be used as a straw for drinking unpurified water. The bolts fire through the center barrel of the slingshot, and are pretty accurate, partly because they're forward weighted. Not that you were going to, but never trust an axe-wielding engineering student again. [Slingshot Channel]