I made one out of a fish tank before. it was a plastic 6" tube one that had fake fish in it. And a light at the bottom that changed colors. Some wierd thing I got for a birthday or something. I cut a hole in the top for a tube and one for a bowl and it turned into a good bubbler. Heh
Once we bought a bathysphere and put it in the Pacific ocean.
We used an empty 55-gal. oil drum for a bowl and a firehose for a stem.
You could get such gigantic hits that usually several people in our group died everytime we had a smoking session.
The only problem was that sometimes when you took a hit you also sucked in a Moray Eel or Barracuda.