Re:DIY Best RED L.E.D. Flashlight?

Goto Radio Shack 
They have a Jumbo Red Led light. around 5000 Mcd data is 
10mm Red LED 
$2.59 Brand: RadioShack 
Catalog #: 276-086 
Typical MCD is 5000. Typical wavelength is 660nm. Size is T3 1/4 or 10mm. Clear
lens color. Viewing angle is 30°. 36mA (max). Typical Voltage is 1.9, with a
maximum voltage of 2.2V. Comes as package of 1.

Some stores are out of stock so look for it in several store. 

Next get cheap 2 AA batteries flash light. 
Take out the lightbulb crush the glass using plier and clean out the cement
base.
Solder the LED into the light bulb base. Remember to keep the polarity correct.
Test first before you solder. 
You can file the top of the LED lens flat to diffuse the light.

I made one from way back in 1995 and has use it constantly since then. Some
people caution me about slodering a small resistor in series to the LED but I
used OLD AA batteries and skip the resistor, It is better this way since the
construction is less complicated. 

You can also built banks of RED Led into a square box and use it as Maplight,
better still solder a small potentiometer in series to reduce the light
intensity. 

Hope this help
Sofjan Mustopoh