First time grower first time posting. I've got a concept in mind. I picked up a 400W HPS ballst and Lamp for $30 off craigslist. The only cabinet I really have around the house is an Armoire 2'deep 3.5' wide 6' tall. My concern is the size of the cabinet for the heat of the HPS. I'm thinking about a DIY cool tube. i want to keep this stealth so I'm thinking about venting the cool tube out the back. My only problem is the intake for the cool tube. If I have it draw from outside the box it will be sucking air that's about 90 degrees or so because my grow is in an attic. I'm ducting an a/C supply to the armoire from my central a/c. So I was thinking about having the tube pull from inside the cab. Is it normal to pull the air for the cool tube from inside the box? I was thinking of attaching my carbon scrubber to the intake side of the cool tube and putting a 140 CFM can inline to pull through the scrubber keeping everything stealth. Worried about insulation for the armoire too. Any suggestions? R Value rating I should be looking for with respect to insulation. Something not too bulky. Basically i'm starting this grow with a budget of $100. so the armoire was free I've got 30 in the light so far and have yet to build the DIY can filter or DIY cool tube but costed the materials out to 70. I'll be into it right at $100 if i can get it to stay cool. Any advice on design while maintaining stealth or comments is greatly appreciated. also light leaks aren't an issue as lights will be on during the day. I work odd shifts. Only way to take care of the girls is to keep them on when I'm home. So instead of suggesting i keep the lights off during the day I need something better than that.