This is a very simple and affordable project. Its really just a toy; great for indoor use and is easy to carry around given its size. I wanted to make a nice small cannon that I could easily use indoors that was really simple to make and operate. It is a mini combustion cannon that fires 5mm BB's really well - they ricochet across a room like crazy.

• Tablet pot/container (e.g. calcium carbonate or vitamin tablets pot)
• Piezoelectric sparker from a lighter
• 7mm Ø (5mm int. Ø), 220mm long pipe
• Two pins/thin needles
• Two rings of 22mm Ø pipe
• A few lengths of insulated wire
• Solvent weld cement or multi-purpose adhesive

To attach a wire to the metal base of the sparker, I made a 'cup' to fit to its end (see photo). I made the 'cup' out of thin metal and soldered a wire to this as you must not solder to the base/end of the sparker as the heat from the soldering iron causes it to fail and stop sparking!! The wires leading from the sparker should be approximately the same length of the tablet pot plus about 50-100mm.




I then drilled a 7mm Ø hole in the base of the tablet pot to allow the barrel to fit through. I also passed the two wires leading from the igniter through this hole as shown in the photo.

To the end of the barrel that is going to be inside of the tablet pot add a very small amount of multi-purpose adhesive to the inside of the barrel - to narrow the internal diameter.

The barrel should intrude about 80% of the tablet pot to minimize its size (i.e. half of the barrel is inside the tablet pot) and I secured the barrel to the inside of the tablet pot with some multi-purpose adhesive.



To make the ignition mounting I used a couple of spilt rings of piping cut from a length of 22mm Ø pipe, and fitted one around the other until it fitted snuggly in the tablet pot.

I then pushed two pins through the side of this mounting and cut the protruding excess parts of the pins (to make it flush when inserted into tablet pot) to create a 'sparking bridge'. I then soldered the two ends of the wires leading from the sparker to each pin (see photos).





I then taped (using insulating tape) the sparker to the side of the tablet pot and also tapped a 'stop' made from layers of card behind the sparker to stop the sparer from moving when the sparker is pressed. After the sparker was fairly secure I wrapped a final layer of duck tae around it, just to hold it in place indefinitely. 

This is just a small guideline to operating the cannon - to get best results you will need to practice and develop you own methods of operation.


• Remove lid of tablet pot and spray a very small amount of propellant into the chamber.
• Load a projectile (I like to use 5mm BB's).
• Fire!