well i wasnt really going to use this cuz im a bit nervous about cardboard and electricity. im just thinking of the concept, like if i made something similar out of plywood or something. like id be able to mak it bigger or wider depending on my needs. id have more space for fans and lighting. since im going to be using cfls, im thinking i could get 2 cfls on each side (maybe more depending on size), and hang a more powerful light from the top. I have a 125 watt cfl but dont have a mogul socket or whatever for it at the moment. but if i made this out of wood does the concept seem like it would work?
I will say for me it is temporary until I figure out what my real needs will be. No pics up here sorry 
I have my intake and exhaust fans ran off an old PC power supply and mounted 2 Surge strips with 2 y splitters-I believe 4- 26 wt Cfls on each strip and side of box lined with Mylar and so far so good-great for a grow or 2? there are easy DIY cabs and set ups for less than 100 bucks----I would suggest more than a cardboard box for longer runs- JMO Thanks and happy growing 