This is now outdated. For the new improved instructable with no soldering needed, go here: https://www.instructables.com/id/Improved-Flashlight-Electronic-Cigarette-no-solder/
If you're giving up smoking, you've probably already tried (or at least heard of) electronic cigarettes - a reasonably effective way of getting hot nicotine into your system, without any of the tar or nasty cancer-causing carcinogens which come along for the ride with conventional cigarettes.
Unfortunately, the cheap ones available from petrol stations and mall kiosks don't last long and produce a negligible volume of vapour.
The more expensive models can produce decent vapour and have a more reasonable battery life, but they are not cheap, and even spare parts come at an inflated price.
This instructable will show you how to build a very powerful vapour machine with long battery life from a flashlight.
The build time should not be longer than a few hours, but significantly less if your fingers are nimbler and your soldering skills are superior to mine.
Step 1: Step 1 - Acquire Your Materials
For this instructable you will need:
A dead e-cig battery - I am using one from a Janty Ego, but others will work as they all have the same basic layout.
An aluminium bodied handheld torch - I am using one from Wilkinson (£2.99), but Poundland ones work just as well.
An 18650 rechargeable battery.
A soldering iron (and solder)
Plumbers mate putty.
About an inch of thin (and I mean thin) insulated wire.
An atomiser or tank system. I recommend this one: http://www.totallywicked-eliquid.co.uk/products/replacement-coil-systems-2/dc-rcs-series/k1-dual-coil-replacement-coil-system-product.html
Step 2: Disassemble the Torch...
Assuming you are using the £2.99 Wilkinson torch, unscrew the switch / battery cover, the torch head and the large spring.
Remove the AAA battery holder from the body.
Turning your attention back to the torch "head," look inside and you will see an aluminium ring resting high up on the internal thread. Beyond this is the underside of the LED circuitboard.
Using a fingernail or the tip of a pen, gently unscrew the aluminium ring until it is completely removed from the head and then turn upside down to shake loose the LED circuit and the clear plastic "lens".
Put all of these parts to one side.
Step 3: Disassemble the Original Battery...
Now we're going to take apart the dead battery from your original e-cig so that we can re-use the connector in our new flashlight.
As mentioned, I'm using the battery from a Janty Ego, but this procedure should be similar on other models.
Grasp the body of the battery in one hand and get a good grip of the connector end with a pair of pliers. Work the connector loose with a rocking / rotating motion.
Eventually it will be loose enough to just pull away. Wires inside the battery will pull and snap, and this is where it becomes important that you are using a discharged battery, because if the battery has charge still, there may well be a small fire.
Pull out all of the wiring from the connector including the circuit board and the switch.
Throw away the parts of the battery which aren't the connector.
Looking at the connector head on from the top, you will notice that the central section is insulated from the side wall by a thin rubber seal.
It looks solid but it isn't, so flip the connector over and with a thin screwdriver or a pen, apply gently pressure until the central pillar and the seal pop out. Give them a quick clean or wipe down with a cotton bud and then put aside the seal and the connector.
Step 4: Soldering the Central Pillar!
This seems fairly simple and straightforward, but as I was starting with zero soldering skills, it took me an inordinately long time. Your Mileage May Vary.
Take your thin insulated wire and strip about a millimetre from the end.
With your soldering iron (and some solder), attach the wire to the (not flat) end of the central pillar.
Push the rubber seal back into the hole in the connector and then feed the wire through the hole until the central pillar is firmly back in place.
Step 5: Sticky Stuff...
Remember the circular piece of transparent plastic? Good. Find it among your pile of discarded torch components and use your soldering iron to gently melt a hole of around 2mm diameter through the centre of it.
Now find the threaded aluminium ring which used to hold the LED circuit in place inside the torch head.
Slice off a thin strip of Plumber's Mait or whatever chemical metal type substance you are using and apply thinly around one of the flat (not threaded) surfaces of the aluminium ring.
Press the transparent plastic circle into this. scrape of any excess from the inside and edges, then go and make a cup of tea while it dries.
Step 6: More Bits...
Back at the beginning you will have removed the battery holder from the main body of the torch. Remove the batteries.
On the upper and lower surfaces of the battery holder, you will notice circular discs held in place by plastic studs through three holes. One of these discs will have a small central protrusion - this is the one you want, So use a small pair of pliers to pull the disc off. Put it to one side for now.
On the interior of the battery holder, there is an array of springs. These can be unscrewed and removed without tools. Unscrew and remove one. Put it to one side.
Step 7: Sticking Bits Together...
The aluminium ring / transparent plastic assembly should have dried by now. Think off the plastic side as the underside and the other side as the top.
From the top, feed the wire from the connector through the hole in the plastic so that the connector sits it the centre of the disc and the aluminium ring is around the base of the connector with a distance of 2mm - 3mm.
Use putty again to fill the gap between the connector and the ring, but leave a gap of about 5mm in one place - the spring will go in there later.
Let the putty set while you go and make another cup of tea.
After your tea, CAREFULLY strip the wire that is protruding through the plastic disc.
Find the metal disc which you removed from the battery holder in the previous step. The bump should press downwards into the hole. But not yet.
Thread the stripped wire through the three holes and now you can place the metal disc centrally on the transparent plastic disc.
Fire up your soldering iron again and press it gently against the centre of the metal disc where id dips, after a few seconds, the plastic will soften and the metal will sink into the plastic. Do NOT let it sink all the way through, just enough to hold it in place.
There is now a direct connection from the central pillar to the metal disc, which will eventually be in contact with the positive terminal of the battery.
Compress the spring you removed from the battery holder and place it into the gap between the connector body and the aluminium ring. Its own tension will keep in in place and there is now a direct connection between the internal wall of the connector and the aluminium ring, which will in turn be in contact with the body of the torch and the negative terminal of the battery.
Step 8: FINAL Assembly
You still have your original atomiser (the part of the electronic cigarette which heats up and produces the vapour) or you've bought a new one. I use a this one: http://www.totallywicked-eliquid.co.uk/products/replacement-coil-systems-2/dc-rcs-series/k1-dual-coil-replacement-coil-system-product.html or else a dual coil mega cartomiser which can also bought from Totally Wicked
Screw the atomiser onto the connector.
Find the (now hollow) head of the torch and fit the aluminium ring into the thread so that the atomiser pokes out of the top. Use the atomiser to turn the entire assembly until it will turn no more. When this point is reached, the atomiser will detach. Don't worry about it for now.
Screw the torch central tube into the head and insert the 18650 battery Screw in the battery cover / switch.
The battery will be pressed firmly against the switch and the underside of the connector assembly and providing tension to prevent the assembly turning when the atomiser is screwed on again.
Screw the atomiser on again.
Press the switch on the bottom of the flashlight to activate your new electronic cigarette.
The battery should last around two days of very heavy ( pretty much constant) vaping before it needs to be charged again, and put out enough power to produce a frankly ridiculous volume of vapour.