i was in your same boat.. so i searched around the internet and found instructions on how to make it out of fiberglass..
i followed the step to the line and ended up with SWEET results..
heres some links
(this guy goes into great detail with pics)
http://members.iinet.net.au/~nismo/subs.html
(so-so tutorial but has illustrations)
http://www.geocities.com/MotorCity/7165/how_to_1.htm
(for all those that want to setup kickpanels)
http://www.sentra.net/solm/december00/kickpanel.shtml