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Today i will show you how to make a simple, but spectacular handheld  flame thrower that can shoot a flame over 4ft (or 1.2meters) long. It would bring a great big smile to any budding pyro out there. Best of all it is so simple.

Uses of this device include but not limited to blasting flies off the ceiling, shooting mosquitoes out of the air, clearing spider webs and their inhabitants, scaring others with the sound of a roaring flame, melting cheese on toast, fire starter, eyebrow removal and anything else your imagination can come up with.

The method is the same as using a lighter to ignite any flammable aerosol whether it be WD-40 or your favorite deodorant, as your spraying it. The concept is the same but with some improvements such as using a butane canister for the fuel, a kitchen jet torch as the ignition and a narrow tube for directional spray, giving you one handed operation, a narrower flame which in turn will travel further and help you hit your mark more accurately while keeping your fingers well away from the flames. The trick to getting huge flames is to have the butane canister upside-down while spraying. This gives roughly 4 time the length of flame as opposed to spraying the can while up-right.

Step 1: Bits and Pieces

Parts:
* Butane can (8oz or 227gram ones used in portable stoves are most economical)
* Kitchen jet torch (or any torch that can stay lit without having to hold down a lever)
* A spray head from some other aerosol spray can
* Thin tube of metal (preferably brass or copper or something that you can solder). I got mine from a hobby store
* Flexible tubing to connect from butane spray head to thin metal tube
* Small flat piece of brass or copper to be used as a heat shield for the tubing (again something you can solder)
* solder
* Bendable bonsai wire
* duct tape

Butane Canister:
I have chosen to use 8oz (or 227gram) cans of butane because they are widely used in portable stoves which means they are readily available and cheap (at around $1.50 AUD/USD where I’m from). Also butane is extremely flammable when mixed with air and the flame will not propagate back into the can because the can does not contain any oxygen (which needed for the butane to ignite). Butane will not leave a residue on surfaces which other propellants would. The only drawback of using such a canister is that it needs to be upside-down when spraying your flame.

Kitchen jet torch:
Has an integrated click ignition, uses a jet light system which is less extinguishable in wind and can be left on without assistance using a gas dial.
Spray head :
Salvaged from another aerosol can, the spray head is used to connect the thing metal tube to the butane can. It is also the trigger mechanism for the flame thrower. Ideally what you want is a wider spray head with lots of area for your finger to press on so that it doesn't hurt your trigger finger after prolonged use (like spray paint can does). The spray area of the nozzle is not important as it will be drilled out to accommodate the tubing.

Thin metal tube :
This exit tube is thin and narrow to give a targeted flame with maximum distance. It needs to be metal or it will melt along with the tubing from coming from the can. It needs to be a metal that is solder able so you can affix a heat shield to the tubing. I got mine from local RC hobby store. it was in a mixed bag of tubing.

Flexible tubing:
Is used to connect the spray head to the metal exit tube. I used something I had lying around but you could also find a small tube in those BBQ lighters with the long neck that sell for about $2 at your local thrift store.

Flat metal heat shield:
This is to protect the tubing from melting and also stops the flames dripping back. You see, when butane exits the canister, most of it is gas, but also some of it comes out as a liquid can sort of drips back down the exit tube. This liquid can catch a flame but the heat shield helps in preventing that.

Solder:
Used to join the thing metal tube to the heat shield

Bonsai wire:
Used to position the metal exit tube to spray butane through the flame of the kitchen torch.

Duct tape:
To stick the kitchen torch to the butane can.

Step 2: Putting It Together

Find a small metal tube and some tubing that will fit snugly around the tube. The smaller the better.

Drill a hole in the heat shield the diameter of the metal tube. It may be easier to also drill two holes the diameter of the bonsai wire into the heat shield at this time.

Thread the tube into the hole. Solder the two together. You can use the kitchen torch for this part.

Attach the flexible tubing  to the metal tube.

Find a spray head for the butane canister making sure it fits by giving it a short spray. Now drill a small hole the diameter of the flexible tubing into the exit nozzle of the spray head.

You will need a way of securing the flexible tubing to the spray head. You will need to make it fairly air-tight. You could use hot melt glue but i used some silicon i had lying around.

Thread the bonsai wire up on hole of the heat shield, bend the end to point back down and thread the wire back the other hole. If the heat shield and tube is loose on the bonsai wire, then you could twist the wire around more so that it is snug.

Duct tape the kitchen torch to the can of butane.

Affix the heat shield to the kitchen torch so that the metal tube is directing the butane to pass through the flame of the kitchen torch when lit.

And that's it you done.

Step 3: Using

To use, light the kitchen torch first leaving it on.
I like to point the flame to the sky until ready to trigger the flame thrower.
Try to aim with the butane can upside down if possible.
When ready, just press on the spray nozzle atop the butane can and blast away. 
There may be some residual gas left in the flexible tubing that stays lit even after letting go of the trigger. 
It’s only a tiny flame could just blow out or you could try shorten the flexible tubing from the canister to the exit tube.

Enjoy and don't burn down your house.