I wanted a replacement for my 250 watt halogen--a lamp which, while sufficiently bright, was so hot that it was impossible to work with for any length of time. Enter the world of high-powered LEDs.
In this Instructable I'll show you how to construct a 50-watt LED lamp. 50 watts doesn't sound like a lot compared to 250, but LEDs are around 5-6 times as bright as incandescent per watt. The 250 watt halogen puts out 3600 lumens--this LED puts out over 4000!
The materials should be less than $100, depending on what you can scrounge together and how exactly you construct it.
The hard parts--the machined mount for the LED--I did on the manual mills at TechShop. TechShop has everything you need for this entire project, even soldering irons and the like in case you don't have one. Most of you probably don't have access to a mill otherwise, so sign up today!
WARNING: Parts of this Instructable require experience with AC line power. If you're uncomfortable with this, get someone to help you out! If you make this at TechShop, just ask around and someone can give you guidance.