I gave a talk on this at the convention in Texas last Summer. And again at a recent UK based caving technology meeting. You can download the (16MB) powerpoint presentation from the UK event from here:
http://bcra.org.uk/proc/cts10/Footleg%2 ... graphy.pptIt is mainly pictures to illustrate the talk, but you can see the internals of the LED photography lights I have made. The LEDs came from DealExtreme.com (
http://www.dealextreme.com/details.dx/sku.12721 ) and the drivers were from Kaidomain.com (
http://kaidomain.com/ProductDetails.aspx?ProductId=6386 )
The main problem with building lights using these LEDs is the huge amount of heat given off. If you do not draw this heat away from the LED then it will not last very long at all. So the take home lesson is to use a metal housing and provide a good heat path from the LED to the housing. The talk also includes some pictures of twin P7 LED lights made using the same LEDs and drivers by UK caver Rob Eavis.
I have also used MagicShine mountain biking lights which use the same LED. Search for them on Google, or on the DealExtreme or Kaidomain websites.