I built my own out of a 2D Mag
Back before the hotlips, I used the Elektrolumens $1.00 aluminum heatsink in which I thermal epoxied a Luxeon Star (Bin R2H) Added a Madmax+ wide open regulator from Wayne Yamaguchi (thermal epoxied under the aluminum heatsink off to the side) The madmax+ puts out around 800-900mA to the Luxeon. Cut the tube off the reflector, wired it up, dropped the heatsink down into the Mag tube around 25mm so the reflector would just touch the LED.
I get 6 to 8 hours out of of a set of D cells, throws 100+ meters. The point of it is for a recumbent bicycle mounted frame light. Works very well and throws very far. Need to get some of that UCL glass to keep me content.
Been using it around 5 hours a week for the last 8 months, it is a great thrower.