I forgot all about gravity bongs, but I actually made one today. Me and my friends were takin hits on my back porch. At first we all just took one each of some mid-grain and it got us pretty blazed. Than after 2 friends went inside I took like 5 more. haha. They can burn up a lot of pot if you dont know what your doing, but once you master it you can get the whole bowl on one hit so theres nothin to burn off when you unscrewing it.

We made ours with a bucket and a 2 liter soda bottle. The last bowl I smoked I got it in one hit and it really fucked me up. Gravity Bongs are fuckin sick.