This is dangerous, do not do it, and it's probably illegal. Click here if you're under 21. You could blow yourself up trying to build a flamethrower out of anything.
Since you're doing it anyway, it is real easy to make a small flame thrower out of a Bic lighter. It only takes a few simple modifications, which can amazingly still be done today regardless of the child proofing spree every product seems to lose functionality over.
And, ignoring the above, it is really hard to blow yourself up. I made these all the time as a kid and never blew myself up. You will learn below why this is very difficult to do with a butane lighter.
- Several Bic disposable plastic lighters, the kind that use a little roller and flint to start (not the sparking pushbutton kind). The lighter must also have the little 'flame height' control on the front, most decent Bics do.
- Small flathead screwdrivers and/or knife
- Wire clippers (optional)
Start by prying the little metal cover off the lighter. The cover is marked "-" to the left, and "+" to the right. Set the cover aside.
Now push the gas button, observe and learn. The button is part of a lever which pulls upward on a little brass nipple that vaporized butane comes out of. Its base is a white geared wheel, around which the 'flame height' control is wrapped. That geared wheel is what we are interested in.
More butane is released when the wheel is turned to the right, less to the left. I'm trying this right now to make sure it still works, and I'm SO surprised Bic hasn't redesigned these things. Turn the flame control to the right, push it upwards, and then flick it to the left. Repeat.
The goal with this is to set the flame to "+", then flick it to "-" while partially off the gear, hopefully making it skip a few teeth. Then when you return the flame to "+", the gas valve will be a few more "clicks" open than normal, and the flame will be bigger by a couple inches. Strike a light and see if it worked! If you can't get the flick trick to work, then you might try cutting off the flame height control (NOT the nipple or the gear it's in!!!) and pushing it right a quarter turn with a tiny screwdriver.
Keep opening the valve until desired flame height is obtained. Now don't go nuts and turn the wheel so far right it comes undone! I was a dangerous kid, but I wasn't dumb. That thing might unscrew or something if you turn it too far right, so we never did it.
You can get a nice flame (57 inches tall) to come out of a reassembled lighter with its own striker. But open the gas much more then that and the gas comes out so fast that the spark wheel won't light it, or it won't stay lit. For these wide open bastards you need to hold another lighter a few inches away from the modified lighter, just like with WD-40.
Make sure to put the metal cover back on. You know have a flame thrower you can carry about in your pocket (if you're brave). What you do with it is your business. Whenever you're "using" it, be careful not to let the lighter itself get too hot. It is plastic after all, and might melt. Although I never saw this happen, and I think it would take some time and dedication to accomplish.
All this is surprisingly safe. If the lighter gets a hole in it somehow, the gas is gone in less then a second, escaping at a rate far too fast to easily burn or ignite on its own. This happened to a friend by accident once to no ill effect. HOWEVER it very well might catch light if an open flame is near! Like another lighter, whatever you were burning, etc! Be careful!