Seen this on another forum and thought it looked pretty cool IMO. The spray will make the box stronger, and also seal up anything you couldnt seal with silicone or whatever you used.
This is a box under the rear seat of a Chevy Silverado.

 

hmmm. . . I know it's ghetto and ricey. . . but is it possible to build an entire box out of this stuff, with some mdf bracing? Fiberglass is a pain to work with. . . and there are those custom molded boxes for subz for certain cars, and I believe that some of them are plastic

 

haha, kinda a haphazard port

but that's really sweet, i'd say it looks great. where is it sold and for how much?

 

He built the box and prepped it (routered edges, filled screw holes with wood putty, and sanded it smooth) and had a Line-X shop spray it for $67.