Fiberglass box in Ranger

Can anyone tell me an easy way to do a fiberglass box for a ranger that isnt permanent.  The truck is a single cab and I need all the leg room i can get.  I have a wood box in there at the moment but it doesn't have enough airspace in it for a 10" subwoofer.  I am also thinking about going to 2 8" subs.  If it would be easy enough to change the box into fiberglass please tell me how.  Thanks for any suggestions.

theres tons of stuff you could do with fg.  if youre looking for leg room, id try to build a box to fit underneath the seats first.  that way it would be totally hidden.  another way would be to make it fit in a corner in the back, or maybe across the whole back behind the seats.  if youre good and want to be crazy, you could even fit some 8s in your doors.  that would be tight, but alot of work.  just in case you dont know much of the fiberglass process, ill give you some good tutorials.

http://www.e-kittan.com/fibre.html

http://web.njit.edu/~cas1383/proj/main/