I've been reading a lot about DIY LEDs on this site and others. I finally was able to take the information and turn it into reality.
I used Cree XML LEDs (16 CW and 8 NW) using three MW ELN-60-27P constant current drivers (each running 8 LEDs). I am planning to dim the LED using a Typhon controller (based on Arduino). If you look at my plan, I used .01 ohm current sense resistors to check my current going through the LEDs. Interestingly, the current that is running on each circuit is about 2.5 amps, even though the MW drivers are suppose to top out at 2.3 amps. I don't really understand that, but maybe someone here will have some insight into that. I used aluminum railing from Amazon and drilled little holes for the wires, which run in the channels on the reverse side of the heat sink. I used LED adhesive pads to secure the LEDs to the heat sinks. Running at 2.5 amps, the heat build up on the aluminum is definitely noticeable, but not too hot to touch. I can lay my hand on the aluminum for a long time without any discomfort.
Here is what I ended up building. It took me many weeks of planning and several days of building, but I think it is finished for the most part (some work remaining for the dimmer if I opt to do that). Here are some photos as well as my plan that I used.
What I have left is to set up the tank with the tank padding (3/4" neoprene), substrate, water, plants, and fish .... in other words, another 3 months of setting up (I think that might be optimistic for how long things took so far). And, yeah, I have to clean the glass first.
Edit #1: the tank dimension is 60x24x24.
Edit #2: I used Cree XML U2 cool whites and XML T5 neutral whites.