I need specs on building a custom hood

[told]

I want to build a custom hood for my 400Watt HPS light. I have a large metal reflecter (generic one, its like half of an octagon) already but this isnt good enough for me.

What i want to do is build a box or something, with ventilation and built in fans. Just like retail air cooled hoods.

I need to know how to go about doing this so A) i dont burn my house down and B) that it works effitiently.

What are the key points i should take note of before i start this project?

[told]

lol, ok so i just winged it with the only concept in mind -- hot air rises. lmao ok so what i did was i maticulously cut a large hole in the top of the reflector, directly above where the bulb is. Godamn this was not easy without power tools, yep i did it by hand... got plenty of battle wounds as a result... moving on, i then securely attached a 50 CFM exaust fan on top of the hole, covering it completly. then attached a tube to the output of the exaust fan and pointed it upwards (the metal tube kind).

I didnt think this was enough power so i upped the anti.

I then took a 30 watt bionaire upright fan, disasembled it to get the guts -- that cylinder fan attached to a roter and motor were what i recieved. It was just what i needed. I then cut a rectangle hole on the opposit side of the reflecter directly in the middle of it, slid the fan in upside down inside the hole, attached it securely. Now there is a nice cylinder fan on one end pushing the air to the other side where a hole on the top with a 50CFM exaust fan is sucking that hot air up and out. I dont think i will be having over heating issues any more

now i must go isoprop my wounds, ill post a pic in a bit.