best bet is to buy a slide-bowl. you can get a plain glass one for about ten bucks...or you can go BIG. I mean a slide bowl that is almost as big as a bong itself...but we're getting ahead of ourselves.

Usually aquarium tubing will work fine for the tube...you may have to experiment a bit, but walmart has an 'aquarium gravel cleaner' in the pet section. It already kinda looks like a bong...its a clear plastic tube with one open end and one end tapered down to fit the tubing. The aquarium hose that it comes with is perfect for a standard slide bowl. Just make sure you drill diagonally!