This project will run you at about $50 not including batteries. There are other cheaper DIY alternatives and production flashlights that may give you the better deal (dollars to lumens), but if you love flashlights and DIY, then this project is right for you.
This modification can be done by a "beginner" with limited flashlight knowledge, soldering skills and a basic idea on how to utilize limited resources.
Other Helpful Links (how I learned to build this):
Candle Power Forums
Budget Light Forums
Step 1: Parts & Tools
- Maglite 2D (local hardware store)
-3/4 inch diameter pvc coupling (local hardware store)
-3/4"x1/2" Reducer Coupling Copper (local hardware store)
-LED-Cree XM-L (Bin T6 or U2- I used U2)
-Arctic Silver Thermal Adhesive or similar item
-Wire Stranded 22 AWG
-O ring 50mm
-small spring (salvage off of old/cheap flashlights)
-insulation foam (2"x2")
-18650 Batteries - Panasonic or any reputable brand will work. Do not purchase ultrafire 18650 batteries despite their price. There are too many fakes out there and the quality of them is terrible. You can also avoid purchasing the Recharagable CR123A's shown in the pictures. [10/12/2013 UPDATE]
-Thick Small Diameter Rubber band
-Hot Glue Gun
-Wire Cutter & Stripper
-Torex T-8 screwdriver
-Pipe Cutter 1/8"-1-1/8"
-2x Small Staples
You Might Need:
Make sure you check all parts before and during assembly to make sure everything works.