Strongly considering modding my 8-bulb setup with a plexiglass cage of some sort. I'll see what they have at the local stores and see what I can come up with. I have the SunStar HTG clone of the bad boy... very similar except the lights do not have switches and the ballasts are between instead of above so there's a gap... none the less, it's working pretty well, save for the fact that I have to be kind of careful about how close I let them get, as I have had a few burns and some wilting on hotter days. (Still dialing in exhaust system, but have been keeping things open air to compensate.)
Question, have you built one of these? I'm thinking that you'd want to hold the plexi off the bulbs a little... I'd like to seal it in with some good air flow, but wondering how far off the bulbs need to stay from the plexi to avoid the plexi heating up... I guess, with a good enclosure and a strong exhaust fan, you could have it almost right on the bulbs and still stay cool... thinking just shy of an inch, and then you have a unit that lets your plants get right up to the 1" distance without any risk of burn. I have an exhaust blower that I am hooking up tomorrow, but now I am thinking I might as well pipe it directly from a hood through a passive intake.