Lego can be used to make all sorts of things like rubber band guns, automatic toilet flushing using the NXT brain and now, a machine gun capable of firing 12 100mm steel balls in under 2 seconds. Why you need to accomplish that is anyone's guess, but it still looks to be cool. As well as seeing the finished product above in an image and below in video format, there are also full instructions included over here so you can go get your old Lego and make your own. Be careful though as 10mm steel balls could hurt.
Via: UberReview