How to put fiberglass & MDF together?

I'm trying to build a spare tire sub box. The box will fit completely inside the spare tire. I plan to use MDF for the face and Fiberglass for the (sort of) tub that will fit in the spare.

My question is, how do I connect the MDF face to the fiberglass tub. I have two plans:

1- Cut the MDF face such that it will fit inside the top edge of the fiberglass tub and then screw in some screws from the side of the fiberglass tub (shaped like a cylinder)  into the MDF and then seal the edges with a sealant (resin?).

2- Make the tub such that it has an inwards edge on the top and screw in the MDF face from the top. The First option seems much simpler and I'm wondering if there's any reason not to do it this way?

Thanks!

Hi ! I m a newbie in this site. I think the following link might be able to help you. This site has a step by step installation photo gallery for you to follow.

http://www.strathfield.com/photo_gallery.asp?GalleryID=7

Cheers!

I just did what you want to do.  My first suggestion is to cut out the spare tire hold down bracket and anything else that sticks up.  Try not to create holes in the tire well.  I just hammered mine out.  Next I would check the volume of the tire well because this will determine if you need to raise the floor or not.  You must consider the components you are using (how many subs,volume per sub).  Make sure you check and calculate the volume before you start fabricating.  I made the mistake of guessing and after I raised the floor and glassed it all in I found that I had too much volume for my setup.  Having too much is better than not having enough, but in my case I had way too much.

Fabricating:  Start by making a frame from 3/4 MDF.  The frame should be positioned so the inner edges are about the same shape as the outside  portion of the tire well.  For my frame, since I had to raise everything 4 inches, I stood the MDF pieces vertically then screwed the frame together outside of the car upside down on a flat surface.  The top of the frame where the main sub board will be must be flat for a good seal.  I then placed the frame back in the car and started on the glass work.  I used 3 pieces of 3ft by 3ft woven glass cloth and 1qt of polyester resin.  I have a small car so you might need more depending on the volume you want.  My theory on the amount of glass needed is the more the better.  Plan on having at least four layers of glass.  ONce you lay all of the glass in let it cure and  the rest is easy.  Just make your sub board from the 3/4 MDF and screw it to the top of the frame using glue on the joints.  You should have a screw about every inch or so.  Once this is done and the glue is dry used silicone on the inside to seal all of the joints.  Now drill a hole for your wiring and route the wires.  Make sure wire hole is sealed.  Now mount the subs and your pretty much done. 

Hopefully I will have pics soon to ilustrate the details.

Good Luck!