How to build a pykrete bong
Pykrete is a strong material made of wood pulp or sawdust that has been frozen. It can be easily formed using water and common pulp, such as toilet paper or paper towels. Basically anything you can mold with this wet pulp will freeze and be extremely hard and cold. This is great for those where a bong is legal; making ice bongs from this material is very simple and straightforward.
A bong is a water pipe, a smoking device, a modern variation to the hookah or Shisha; a long tube passing through an urn of water that provides filtration and cools the smoke as it is drawn through. In this case the Pykrete is not only used as the construction material but replaces the water to further reduce the temperature of the inhalant.
Materials required 
- An entire roll of paper-towels.
- A ready supply of water.
- A freezer large enough to hold your completed bong.
- A bowl and stem for your completed bong.
Basic: The structural inner tube from a roll of paper towels.
Advanced: A length of PVC tube that is the diameter and length you desire for your completed bong.
Basic: Take the tube from the paper towel roll and wrap 15-20 feet of paper towels around it while continuously applying water. Freeze the cardboard tube and paper towels.
Advanced: Take the PVC tube and wrap 15-20 feet of paper towels around it while continuously applying water. Freeze the PVC tube and paper towels. Once it is frozen, thaw for 5 minutes to allow the PVC tube to be removed easily.
Both methods: Once you have the tube of ice, cut smooth ends with a serrated knife. You can then 'weld' a bottom onto the tube.
Take a square of wet paper towels that are folded to a thickness of 15-20 layers and put the wet square on the smooth end of your pykrete tube. Put that in the freezer to harden. Once it has hardened, you can trim the square down to a circle.
Now you have a half closed cylinder made entirely of pykrete. The next step is to create the hole for your stem. You can either use a drill bit or a knife to make the opening.
Once you have an opening big enough to fit your stem, insert the stem into the hole. Take a small amount of wet toilet paper (it works best for detail work) and wrap it around the stem to create a tight seal. Carefully remove your stem and re-freeze the bong. Be sure to avoid messing up the wet opening.
Once the seal is completely frozen, use a knife to shave a little bit off the inside (this is because the pykrete expands a bit and will not be big enough to fit your stem).
Once the bong is completed, insert stem and smoke.
Prolonged storage in the freezer will cause the bong to dry out due to sublimation. Simply re-wet the bong in a sink and allow to refreeze.
A highly recommended customization is to use a foam beer/can cooler that will fit around the outside of the unit. This will give you a dry place to grip and also keep the bong from melting from direct contact with your warm skin. Add food dye to the first few layers during the initial watering to create vivid, colorful patterns. Take care not to use too much as it may stain if the bong is left out to melt.
Place the bong vertically on a saucer or small plate to give it a stand. It will freeze to the plate and give it a sturdy base that will keep it from dripping on your floor.
Do not add water - This will melt the pykrete and leave you extremely messy. Since it is made entirely of ice, it will cool the smoke tremendously! There is no need for water. However, it is possible to embed plastic in the unit during creation and create a water tight inner chamber where you can put water. That water will get extremely cold due to it being surrounded by ice.
Do not leave bong out - It will melt into a big sloppy mess.
Bongs can be used to smoke various substances. At least one of these, cannabis, is illegal in some countries. Be aware of local laws.
Smoking any substance can be fatal to your health, and may result in lung cancer, emphysema, bronchitis, and other respiratory deficiencies.