Here is a pic of the stand and canopy I made for my 40G long, which I later modified to fit a 75G (built a new canopy too). Dont have a construction pics but here is the final product. Its just pine over a 2x4 frame, stained with country maple stain and polyurethane. I'll be soon building a stand for a 150g and 240g and I'll take pics of the whole process but it'll be a while yet probably.
Yeah, it quite big as it encloses the metal halide pendant lights, actinic tubes and cooling..plus, room to move around and work freely without having to move anything.
Its made out of MDF, stained and PVC Glue bonded to waterproof..