Using a waterproof flashlight / torch as a waterproof battery pack.

Описание: Poundland sell a few different versions of this flashlight throughout the year. They do the traditional tungsten version as featured here, an LED version with one or more LEDs in it (usually just one) and a different style that is a bit more angular, lighter and less rugged.
The LED version is OK as a general purpose low level emergency torch, since the single LED does not put out a huge amount of light, but the tungsten one is slightly perplexing, since it is just a reminder of all the problems of the older tungsten torches. Light output that dwindles rapidly as the battery discharges, and really low battery life.
However, the tungsten version of this torch has an ace up its sleeve in that it is very hackable to make waterpoof outdoor battery holders or even have electronic modules potted into the head of the torch for things like outdoor lighting.
This video is just a disassembly of the torch to show how it comes to bits and how it can be reused.
It should be noted that the tungsten version is easier to connect your own loads into than the LED version which relies on the negative connection from the body of the torch being screwed hard against the back of the PCB.