My latest designs have been all-in-one, with the LEDs, driver and batteries all in the same case. The one featured here has 3 Cree XP-G LEDs, 4 lithium ion cells and a driver board from TaskLED.
Prompted by the snow in 2010, I have made smaller versions with a single LED and a single lithium ion cell, which are more suitable for head mounting. Just great for a night ski trip up a local hill after xmas dinner!
A view of the back of the light with the switch. Sometime I may add a couple of charging contacts so that the light can just be placed on a base to charge, until then the back needs to be removed to gain access to the battery.