Alright, this is a great way to make moonlights. Go to your local auto parts store. Most of them sell LEDs these days. You can buy a 6 pack for like 5 bucks. Blue look this best, IMO. Buy as many as you want and take a strip of 1/4 plywood and drill holes just smaller than the leds, wherever you want to place them. The LEDs will stick out of the plywood and all they will holding by is the solid wire at the base of the LED, because the strip of wood will be screwed to the inside of your canopy after you wire it. The nice thing about doing it this way is you can point them wherever you want, like at certain rock structures or corals. Wire all the pos. together and all the neg. together and connect to a cell phone charger or other dc converter you have laying around.
Heres my first reef tank, I built this in like 2 hrs. I am no expert but I have this in my new tank 2 years later and and they still look amazing.