The entire canopy is made from 3/4" birch plywood. The only exception is the thin piece that makes the back of the narrower area is 1/4" luan to allow maximum clearance for light bulbs (every 1/2" counts with such limited space!). The overall hight is just 3.5", allowing .25" of overlap so it won't fall off, 2.5" of inside clearance for lights, and .75" for the thickness of the recessed lid.
We will be installing (4) 48" NO fluorescent bulbs with two ballasts mounted on the back of the canopy. We're using a sheet of mylar for a reflector.
Due to the mitered corners, the recessed lid, and the thinned edges where exposed, you don't notice it is made of plywood unless open, as you don't see the plys. For anyone with access to a table saw, I strongly recommend plywood as it is much straighter and more stable than solid wood of similar size, due to the criss-cross grain orientation of plywood. Also, you will find that a nice piece of plywood is no more expensive than an eqivalent amount of pine 1x material such as 1x4s or 1x6s.