A guy in our local OS did a presentation on basement tank growing chambers. His demonstrator was a wood and plastic box with a glass front - probably equivalent to a 30-gallon fish tank - lit with my LEDs. With no additional heating, he is able to grow lovely little cool-growers - the kind I find impossible to grow. That inspired me to try, but then it occurred to me that a warm "incubator" would be better for the plants I currently have, so…
I started with a hydroponics flood tray - 3' x 6'
I have a false bottom in it (two layers of red EcoWeb, shipped to me by mistake), with an overflow drain in the side.
Then using 1/2" thick, foil-faced foam sheathing, I created an enclosure 2' tall over it, making the floor-to-ceiling distance about 30". I spray painted the interior side of the foam panels white to disperse light better than the foil would, then assembled the thing with duct tape. The front has sliding glass doors to allow access. Without the glass, the whole thing weighs about 20#.
There are eye-bolts through the roof that support two 48" Philips GreenPower "Production Module" LEDs, I have some muffin fans for air circulation, and there is a Mist-King system, with three double nozzles suspended through the roof as well. Additionally, there is a 2' x 4' heating mat controlled by a thermostat and tied to the same timer as the lights, so I get a bit of overnight cooling.
It's been operational for about a month, and there are a bunch of phal seedlings in sphagnum, a phrag flask I got from Fox Valley Orchids, now in S/H, and a bunch of mini's I got from Ooie Leng Sun at the SEPOS show. All are doing great.
Maybe the cool-growing chamber will follow - but likely on a smaller scale.