This is the plasma rifle I made for my Fallout 3 outfit. The base is a Nerf gun and most of the various parts are either from garage sales or a hardware store. It even makes noise if you pull the trigger, but we have to work on that a bit more before it works quite right.
never liked the design of the Fallout 3 Plasma weapons, I think they look far to steampunkish & fragile. the original ones from fallout 2 & it's variants were much better.
I'm glad you like it! The best way I've found to make things so far is to find the closest real world part and mod it. I'm not quite up to the whole "sculpting my own stuff out of plastic and whatnot" stage.