I need some advice on constructing a sub box that will hold my 12" Eclipse woofer in the driver's side rear trunk cavity.

How did you secure the box to where it won't budge when I drive like crazy?

If anybody would send me some dimensions or a design for a sub box that you have built, that would be great too. I'll fudge the dimensions a little to get the exact volume correct for my application.

How did you seal your box to where it is air tight? I figure I'll use some silicone cauk on the joints.

 

For cubbyhole boxes, I typically use a combo of 3/4" MDF (For the baffle to mount the speaker) and fiberglass.

Most MDF only boxes I seal with Liquid Nails, works awesome for subwoofer enclosures and seals them right up.

Don't use Silicone to seal speakers to enclosures, it can react with the speaker surround/seals and cause problems. Most subs have their own felt seals that work well, and if you want extra sealent, then use some Plumbers Putty.