It had to be done. All my Robots have built in water sprayers to encourage young over enthusiastic youngsters to not get to boisterous, however non of them have much power, cue the mini gun accessory. Basically it is a high power water cannon which is controlled from a should mount on the droid. Via radio control it can pan left and right and the main barrel spins up just like a real mini gun. There are small LED strobes in the barrels and it gives a great effect when running, although most kids dont notice that as they are far more distracted with the amount of water it can push out.
The gun is made up from junk, some old alloy tube, tent poles an old cordless drill and some bits of MDF. It is all very simple. The drill is powered either from its own battery pack or draws power from the Droids. The should mount is servo controlled so it can pan and tilt and when mixed with the head channel on the radio will pan as the head moves on the Droid giving a tracking effect. Water spray comes from a car windscreen washer bottle pump powered from the droid and triggered via an RF wireless switch. Using an old cordless drill as the barrel power means that I can make sure it is safe if small hands are placed in the way of the moving barrel. The old drill has a clutch system so any object placed into the path of the moving barrel with simply make the clutch slip, ensuring safety for small fingers.
Since I made this model it has been revised over the last year and now boasts a eiffel stock so it can be used hand held by a costumer. It also has a built in lithium power supply making it much lighter. The water supply has also been upgraded and it can now be used hand held with a camel back water supply.