A useless invention created with office supplies repeatedly swings a ball bearing around a pencil for no apparent reason. The device is powered by tension from a rubber band and appears to be held together by binder clips.
After seeing this concept online, during my lunch break I decided to make my own. After a bit of fiddling with Pencils, a pen, a paper clip, rubber bands, spring clips, and a ball bearing, I came up with this.
via Boing Boing