Hey Judo....I actually paid a local stereo shop to get it fabricated when I got my amps, components, and the interface installed, because at the time, I didn't know too much about car audio. If I could go back and do it over again, I would've probably done it myself to save some bucks.
The box is actually made of wood, and it doesn't seem to difficult to build at all. The one thing that I wasn't too happy about was the fact that they sawed out the storage compartment area to make some extra room for the box to fit. No big deal though, because I don't ever plan on taking the box out.
Another thing too is that the box is not really anchored down to anything except for a couple of long screws that they drilled through the inside of the box into the plastic on the panel. The screws actually keep the box pretty tightly secured, but I don't think it would hold it down if I got into a wreck. I was thinking about maybe chaining it down to the D-ring on the floor of the cargo area. Anyone have any suggestions?