You can do a lot of cool stuff with fiberglass. It all kind of depends on where you want the sub and if you want your spare tire still.
http://www.tccustomz.com/inc/sdetail/94
This is a pretty cool looking fiberglass enclosure that wouldn't be to difficulte to duplicate.
http://www.tccustomz.com/inc/sdetail/94
This is a pretty cool looking fiberglass enclosure that wouldn't be to difficulte to duplicate.