I think it took 3h to build it.
It runs with a single 1.2V nimh AAA battery and the LED is direct driven.
The whole pen is made of aluminium.
Since I don't own a turning lathe I used an old drill machine.
Well I don't think I have the time to build more of these. Besides there are a lot of cheap pens for a few $ on the market.
Here are more pics
http://ledstyles.de/ftopic3560.html