Maybe this is a silly question, but do they have commercially made gravity bongs? It would be cool to have a gravity bong that doesn't look like a budget meth lab or something.
you could make a nice grav with the right tools. The gravtron is just a bottle with the bottom cut out for example. If you get a glass drilling bit, you could drill a few hole on the bottom of a bottle, make a hole for a female slide piece to fit in on the top, then get a slide and you have yourself a cheap, custom, glass grav that you actually put effort into making. It could be a fun stoned project one day.... or you can just buy one.
Yeah, a decent maker of glass (black leaf) makes this waterless suction GonG grav bong you might look into, im going to buy one soon, its on EDIT.
I have a glass on glass PHIRE gravity. It's sick as fuck. Look towards the end of this video to see it in use. [ame="http://www.youtube.com/watch?v=VltU-E6-dbo"]YouTube - Trades[/ame]