Alright i was thinking a box the size of 4' deep 4' wide and 5' tall. the extra height gives me a better way to hang the light without sacrificing too much grow space.. The light i bought was a 300watt led(manufacturarers say its good for flowering and vegging) they say its optimal for a 3' by 3' area so if i use 5 gallon pots(approx 12inch tall) Ill have the 3x3 area covered while the extra 6inches on each side give room for fanning and work space. I have a 190 cfm exhaust carbon filter combo. the box would be 80cubic feet. so thats roughly 2.3x the air is being withdrawn out. i would use soil as the grow medium and line the sides with mylar. i have a timer that would be positioned on the outside of the box. Questions i have include. What should the box be made of? Is this a decent setup? What am i missing?