Step 1: Gather your materials
Besides the LED you will also need a driver circuit. Since the plan is to build an LED replacement for a low voltage lighting bulb, we need a driver that can handle an AC input. Low voltage lighting uses a transformer to reduce the typical 120VAC power to a "low" 12VAC level. www.ledsupply.com conveniently sells an AC capable "buckpuck" that will accept 12VAC input and output a regulated 0-700mA output current for driving strings of LEDs.
So go ahead and shop at LEDsupply or equivalent to get the electronics parts. If you want to be able to dim your LED bulb you will also need a potentiometer. The Endor Star will need to be mounted on a heat sink, such as a section of aluminum angle or channel extrusion. This will require holes to be drilled and tapped as well as screws, heat sink compound, and some wire.
1. Power led such as a 3-up Endor Star with 3 Luxeon Rebel 90 lumen LEDs
2. Constant current LED driver with AC input ability such as BuckPuck 03021-A-E-700
3. 1.25" section of aluminum extrusion for heatsink
4. 4-6 screws fro mounting LED to extrusion, 6-32 works great
5. Tap for threading holes for screws, 6-32 tap works great
6. Heat sink compound for mounting LED to heat sink. Since the LED is isolated, you can use a metallic based heat sink paste like molybdenum anti-sieze
7. Some wire to hook everything up
8. Soldering tools and a clue