You will need:
- A thick plastic canister. (the thicker the better)
- A tube. (Aluminum works the best but plastic can also do the job)
- A piezoelectric igniter.
- 2x metallic screws.
- Plastic coated wire.
- Epoxy (or similar).
- Sandpaper (optional but recommendable)
Important: The canister will have to deal with a strong pressure so you must avoid using plastics which can easily shatter, a hinge lid will open releasing the pressure if the barrel gets stuck with no consequences for the person who uses it, a threaded cap won't let the pressure go out, even most of the canisters can easily hold the pressure it's recommended to use one with a hinge lid.
The bigger the canister it is the smaller the explosion will be, this is because alcohol requires a small volume to quickly rise up its pressure and temperature (Ideal gas law), the optimal volume is around 15cc and 30cc, to calculate its volume put the canister in a scale and zero it, the weigh of the water in grams will equal the volume in cubic centimeters.