So before I launch into several pages about sticking the nobly bit to the long bit and painting the whatnot I figured it might be quite useful to define some names for the parts. These may or may not be what the 'prawns' had in mind but this is my interpretation of it. Feel free to argue where your ideas differ but I'm not listening :P
The barrel, Stock and Handle are fairly standard gun parts so I'm on safe ground there. The front of the gun has a stuck out bit which looks like the pilot flame for a flamethrower. I call this the spark generator (not to be confused with Sparc International mind you!) The nobbly bit reminds me of the high voltage electricity stuff, so I call this the cascade tower. The bottle on top of that I call a reservoir, conveniently placed to slowly drip stuff into the tower. The bottom cylinder is below the gun so presumable injects stuff upwards, hence becomes the injector. Finally the large cylinder on the back of the weapon reminds me of a power cell.