this is an excerpt from http://www.marijuanalibrary.org/brain2.html
"While most users are familiar with varying potencies of marijuana, many are only vaguely aware of differences in the efficiency of various ways to smoke it. Clinical studies indicate that only 10 to 20% of the available THC is transferred from a joint cigarette to the body. A pipe is better, allowing for 45% of the available THC to be consumed. A bong is a very efficient delivery system for marijuana; in ideal conditions the only THC lost is in the exhaled smoke."

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so if you are trying to save money by not buying papers, make a bong, it'll make your bud go longer which mean you save MORE money every time you use it. for a page of good instructions check here, http://www.blurofinsanity.com/bongdesignpage.html there are a bunch of good designs here, find the one that best suits you!