Stupidly easy to make.
1.) Transmission radiator ($40 at Autozone!)
2.) Pump of some sort
3.) Reservoir with clean water
4.) Water chiller
5.) Hoses
The water chiller could be optional, its needed if your going to be cooling more than 1000w of lighting. My rule of thumb is no more than 6 lights per 1hp of water chiller. As long as there is enough water so the water doesnt heat the reservoir up too much while its being used. It'll all come down to reservoir capacity and the amount of water you move to determine how cool it gets.