ok... got the basic shape of the left insert ready. The beautiful thing about fiberglassing these things is that you cna get the basic form pretty rough. Once you get it glassed it's easy to add filler here and there to get the majority of the details in there.
I still need to put in the hole for the speaker.
After this, I will cover the whole plug with aluminum foil, put the MDF ring on it, and then stretch my spandex over it to refine the contours.
From there it will be time to get messy and start laying on the fiberglass.
Once it's cured, I'll start sanding and adding the putty to make it exact and to get all the edges just right.
Then when it's pretty much done I'll cut the box in half, remove the foam form and screw in a piece of flat 2" aluminum all the way around the inside of the box leaving a tab for the other side to screw onto. It will get a good coating of sealant, undercoating and a bit of spray foam insulation before the halves get put together.
The speakers I'm using only require .69 cu/ft of sealed air in the compartment, so I'll add spray foam in the corners as necessary to take up the space.
all for now...