This is version 2.2 of my newest project, a four-barrel gatling gun. You cock and load the barrels (basically a shortened version of my earlier pistol), grab the handle, and give the wheel a spin. This is a much improved version of my first stab at a gatling gun, which had less power, broke more often and was harder to use.
Note: The first picture is upside-down. You can hold it like that, but it works better when held the other way.