Custom fiberglass box for 12s

I'm not sure I completely understand what you're asking. The way i'm understanding you is that you're going to first build the box out of MDF then take off the front side of it then mount a ring and stretch fleece and fiberglass over that? is this correct? It seems to me like that method should work although it seems a little excessive. I'm not sure what look you're intending to go with with this. Have you figured out yet how big you need this enclosure? Also a ported box is a difficult first project as you need to be very precise with volume and calculation. an idea that came to mind for me was to just keep the mdf box together and build a fiberglass top for it like in this post https://www.the12volt.com/installbay/forum_posts.asp?tid=73856&PN=2 Maybe some pics of the trunk and exactly what you're looking to do and people should be able to help a litle more.

Plan the enclosure out on paper or on the computer & make sure that you account for the total volume required for both subs, the displacement of the subs and also the length and displacement of the port(s). After this start witht he base of the enclosure and work your way up and follow the plan that you have. The main difference between the enclosure that I did and the one that you want to build would be the volume for a vented enclosure and the placement of ports in the enclosure, other than that, the fabrication process will be very similar.Jeff

Velocity Custom Home Theater

Mobile Audio/Video Specialist

Morden, Manitoba CANADA