1. The base is filled with water, the amount depending on the size of the bong. Sometimes other liquids are used, although alcohol and oils filter out a certain percentage of the THC when used for smoking marijuana. More rarely, liquids like Pepsi and herbal teas are used; however, such liquids can make cleaning difficult and time-consuming. 2. The substance to be smoked is packed into the bowl and ignited. Cigarette lighters are usually used for igniting the substance. Sometimes matches are used, but they may produce an unpleasant taste, and are less reliable than lighters. In smoking marijuana, it is also possible to use a low temperature soldering tool to light the substance to be smoked, or even a magnifying glass in order to heat the substance to the exact temperature at which it burns, thus avoiding any over-heating and therefore, theoretically, loss of THC. 3. The user places his/her lips on the mouth piece, forming a seal, and inhales, causing the flame to be drawn toward the substance. An inhalation is known as a "hit" or "rip." If the smoker is using a larger bong, the first hit contains no smoke; Its purpose is to draw the clean air out of the chamber and to start drawing in smoke from the bowl. If a smaller bong is being used, the first hit should consume most of the smoke. 4. When the user feels that they have inhaled a satisfactory amount of smoke, he or she can pull the bowl out of the bong to introduce "clean" air. This is known as "clearing" or "pulling the slide." Other bongs have a small hole, known as a "carb", "shottie" (in Australia), "rush" (in New England), or "choke", above the water level, to be blocked with the user's thumb until he/she draws enough smoke to fill the chamber. 5. Once the chamber has been filled with smoke, the slide bowl is removed (or carb unblocked) and the smoker inhales sharply, drawing the smoke into their lungs.Bongs can vary greatly in their shape, material, style, color, and size. Commonly constructed from metal, acrylic, ceramic, or glass, bongs can also be fabricated from materials as diverse as pykrete or even from household objects such as empty water bottles. Some people even make bongs out of fruits and vegetables that are discarded after use. Many bong owners take pride in giving original names to their smoking devices. These names usually reflect cannabis culture or some particular distinction of the bong.Since the bong is such a simple device, it can be constructed out of nearly anything that is at least semi-rigid and can be made airtight. This includes, but is not limited to, bamboo, plastic bottles, soda-pop cans, buckets, vases, beer bottles, hollow plastic and ceramic statues, chemistry beakers, snorkels, even apples and potatoes. However, care should be taken, as burning plastics results in the production of dangerous toxins. Most bongs purchased will be made out of glass (either hand-blown or cast in molds) or clear acrylic tubing. Most of these bongs will include or otherwise utilize glass stems and bowls. However, cheaper bongs (nearly all made out of acrylic) may be designed with metal stems and bowls.A common home-built bong is made from a bowl and stem purchased either from a head shop or a hardware store, or fabricated from supplies around the house. (A bong can be assembled out of tinfoil and a short length of garden hose, for instance.) The rest of the design needs nothing more than a knife or scissors, a 20 oz to 1 liter empty plastic bottle, and some duct tape. The bong can also be made using the burning tip of a cigarette, to make the holes in an easier way. Just because a bong can be constructed this way does not indicate it is a good idea. To avoid dangerous fumes and chemicals, all bowls and stems should be made of glass or metal, and the chambers of the bongs of glass, metal, or acrylic. This type of bong is often referred to as a MacGyver, after the TV show, due to its improvised and home-made nature.