you will need:
1 x metal flashlight
1 x 6mm brass tube (or similar metal tube that fits a 6mm BB)
1 x schrader (tyre) valve - it can be threaded, ripped from a bike tube or be one of those rubber tubeless snap-in ones
1 x JB-Weld, araldite or similar epoxy
1 x superglue
1 x bike pump or CO2 inflator or air compressor
Hot glue gun
Click HERE for an animation on how it works.
There are a few small bits and pieces that may be required but they can generally be found around the house, in the garage or can be bought for cheap at a hardware store.
STEP 1: FINDING THE RIGHT FLASHLIGHT
For this build you do not need an expensive Maglite or branded flashlight, the most important feature of the flashlight is that it has to be metal. The next important part is that it has a threaded cap on the end for changing the batteries; this cap must also be made of metal and it should have an o-ring around it so the seal is watertight. The only other requirement really is that the flashlight has the push-button/switch to turn it on mounted in the end cap, if the on/off button is mounted on the side of the body then the flashlight can't be used for this build as we intend to use the flashlight body as an air tight chamber.
Flashlight check list:
1. Flashlight is all metal.
2. Flashlight has a threaded cap for the batteries - this is required so the valve of the gun can be removed from the gun in case it stops working
3. Flashlight has an end-mounted on/off switch and not a switch mounted in the main body.
4. Flashlight body is a cylinder and not some weird shape; e.g. a conical cylinder that tapers at one end (this does not include the flared end that houses the light bulb as this can be removed and is not part of the flashlight body)