For many days i haven't made something that will be portable , handy and very useful in emergency purposes.I am much interested in making portable gadgets like cell phone chargers ,Flash lights etc etc.. This instructable is about building a sturdy robust DIY flashlight . This instructable uses a steel pipe for its case ( very very sturdy . can even survive if run over bye a car!!!) i have also added a plastic cover to it for finishing purpose.

Step 1: Parts......

1) 1x super bright led operating about 3-5v range
2) 1x 1N4001 - 4007 diode
3) 1 x cell phone charger connector pin( female)
4) 1x resistor of abt10 ohm or try( the led resistor calculator online )
5) 1x circuit board ( or PCB if you ll get one!)
6) soldering iron
7) wire cutters ( also you will need cutters to cut short the circuit board)
8) some small plastic bottles or a large heat shrink tubing ( to cover the steel case)
9) some insulating tape
10) lens for led ( make its focus wider) very use full
11)some glue
12) 1x switch
13) a drilling machine or a pointed screwdriver ( to make hole on the plastic case for the switch)
14) a li ion battery 3.7 v ( like the one in my previous instructable https://www.instructables.com/id/Rechargeable-wallet-LED-torchwith-usb/)

Step 2: Procedure.... Cut the Steel Pipe

Cut the steel pipe to about 7cm in length ( you will need to grind it later ).take some insulation tape and cover the interior of your pipe with it.

Step 3: The Circuit

build the circuit on the basis of the below circuit diagram. connect the battery, the diode, the female charging pin , led etc as given... any problem in the circuit please let me know!

TIP!! :-) place the components as close as you can so that the circuit board will fit in the steel case)

Step 4: Installing the Switch

drill a hole in the plastic case as shown in the image!...place the switch and wire it according to the circuit diagram

Step 5: Finishing Steps

you may need to grind thew circuit board on the sides to fit in the steel pipe.
place the circuit board in the steel case and also place the led and the lens over it.
you will need to glue the case from the top or just secure it with a duct or transparent tape.
so that you can hack it open something goes wrong...

Step 6: Future Developments

you could add a heat sink for the power led .. i did not coz "it would have hampered its portability .. also you could add a micro charger controller for you battery .......i did not coz we are working with a very small battery and it hardly get heated... i have tried charging the battery for the entire night but still no explosion or leaks from the battery works fine for me..!!