this is a head for my custom jielde lamp.

 
it's basically a led cob on a server heatsink and this square to hold everything tight and the place to put a nut to screw it on the lamp.

I made the square quite too short for this heatsink to be sure it will fit but I need to use my dremel a bit to put the heatsink in it. 

Please excuse my bad soldering on the photos

edit: this design is good for what I wanted but get really hot and the only airflow on this heatsink is on the side where my print is, so not the best if I want to add a fan