Here is a step-by-step guide on how to make a homemade bong:

1. Choose a plastic water bottle of your desired size. Remove any labels and clean the bottle thoroughly.
2. Create the bowl by using an aluminum foil and shaping it into a bowl shape.
3. Make a hole in the bowl using a toothpick or a needle.
4. Create the stem by using a pen or a pencil and removing the ink cartridge.
5. Create the filter by using cotton balls or pipe screens.
6. Make holes in the filter using a toothpick or a needle.
7. Attach the filter to the stem by wrapping it around the end of the stem.
8. Enjoy your homemade bong!

[Here](https://timdesigners.com/making-a-homemade-bong-step-by-step-guide/) is a link to an article that provides more detailed instructions on how to make a homemade bong.