custom built grow box

I am thinking of building a box in my closet using wood from home depot and painting the inside of it flat white....I have a 400 watt econo wing hps lamp.....three plants still vegging only 2 weeks....I also have a fan...I was wondering if this is the best way to go or should i leave just open in my closet air...oh im using soil. Does this sound like a good idea?

What size will the box be? I believe hps lights give of a lot of heat so you'll need a fan (which makes noise, I presume because its in your closet noise is bad. I could be wrong). You'll also want to put it a distance away from the plant so it doesn't get burnt.

noise isnt a problem live in my own apartment....i have a fan that blows on the plants and light now.....how far above the plant you think? The Box is 5 feet tall, 3feet wide. would I have to cut ventelation in it or could i just put my fan it? Maybe I should screw the Box and just leave it in the open air in my closet it jsut that the closet is a walk in and i feel like there is too much open space and it is losing light.

I think you should get a thermostat that record max and min temps for the box through a whole 24 hours. That'll tell you how much ventelation is needed and whether or not you need to cut a hole. Do you have pics?

There are some good tuts out there for home made grow boxes, do a bit of googling. I'm only new to this so I can only regurgitate what I've read, I've no experience on the subject (although I will soon ).