Was just going to publish the same thing -
How to Make a Bucket Bong (gravity bong)
Also known as bucket bongs, beach bongs, and depth charges, this is essentially a device that uses gravity and air pressure to draw the smoke into a large chamber and then expel it quickly into the lungs. This gives much larger hits than most instruments, and it is possible to get quite fried quickly with a relatively small amount of weed.
This is how we made ours:
I've smoked out of only a few gravity bongs in my life- but they all were constructed in the same method. And there are only a few I've seen for commercial sale, so here's how to make your own.
Equipment:
A 2 Litre Plastic Soda Bottle (preferably transparent)
A 5 Gallon Bucket
A 5/8" Socket from a Tool Set
A Knife to cut the Soda Bottle
A Normal Screen used in Marijuana Pipes or Bowls
Cut the plastic bottle at the very bottom where it starts to fold in on itself and form the bottom. Cut the whole bottom off the bottle.
Next, put the screen into the 5/8" socket. This is your bowl. Think we're crazy? This size socket fits PERFECTLY into the mouth of the soda bottle. You can try any other bowl that will fit- some head shops sell rubber corks with a hole in the middle for a metal bowl. Another cheap alternative is a rubber hose with a cone piece that fits at the top.
Place the bottle into the bucket and fill the bucket with water until it reaches close to the neck of the bottle. That's it!
Smoking:
Put a lighter to the bowl and gradually lift the bottle out of the water. The slower your lift the bottle, the more concentrated the smoke will be and vice versa. If you do it perfectly, the smoke looks like it's raining down the sides of the bottle- it's very beautiful when you're stoned.
Once the bottle is full, remove the bowl and place your hand over the top. It's now time for someone's turn! Put your mouth over the opening and let the bottle fall to the bottom of the bucket.
Don't try to suck the smoke in- Open your lungs and let gravity do the work. If you inhale or push the bottle down too fast, you might get a mouthful of bong water.