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How to make a gravity bong
Find an empty plastic bottle.
An empty water bottle or liter of soda will work. You can use any size bottle, but keep in mind that the bigger the bottle, the bigger the gravity bong hits will be.
Choices:
(a). If you are using an empty bottle, ensure that the nozzle is clean and dry before you use it. If you're using an empty bottle, use a zip lock or a sheet of tin foil.
(b). Cut a slit and feed all of the plastic in the slit into the bottle. Make sure that you cut tight enough to keep the plastic in place if you're using an empty bottle.
(c). If you're smoking alone, a small plastic bottle should work. You may want a large plastic bottle if you're smoking with multiple people.
(d). Put on rubber gloves to avoid snapping the plastic skin of the bottle. This won't break the bottle.
(c).