This pipe I actually had the idea for when I was working on another video game controller piece (which still isn't finished, lol) but was simple to do, and turned out pretty well.
Basically the idea was to be able to smoke out of the NES Zapper (Orange 'Duck Hunt' Gun). And since no water chamber or anything is involved it was surprisingly simple to do!
What I did was open it up (splits right down the middle into two half-guns). Once inside it was a simple matter to strip the extra stuff in there, and cut away some of the plastic in the barrel. Then, because it would be way to hard to make the entire inside air tight, I just ran a hose down from the tip of the barrel to where the cord originally was in the handle. The idea being that you smoke out of the barrel, and the bowl is in the handle.
The only dificulty I ran into was attaching the bowl. Due to space limitations I had to attach the metal bowl right to the plastic tube, which bothered me for 2 reasons. The first being I that I wanted to keep the screw-bit of the stem so I could screw on and remove the bowl, which wasn't a big loss.. But the second was more serious. Metal bowls heat up, and since it was attached to plastic which is toxic when smoked, I had to add a heat sink, which is just a copper coil wound around the inside of the bowl and off to the side.
Apart from that I just reglued in the trigger, and put it back together. I wish I could have maintained the spring of the trigger you could actually pull back, but there is just no room inside the gun for it.
Anyways, it pulls quite well, and I really like how clean the piece turned out.