What is it and where can I get it? Also where can i get some carpet that will match the stuff in my car already?

 

The wood you want is called Medium Density Fiberboard or MDF for short usually for subs bigger than 10" use 3/4 inch. The carpet should be available at any stereo shop but they may have to order it

 

You can get the board and the carpet at lowes... probably home depot as well...

 

I did, the carpets thicker too. me likes it
MrGone

buy it at the homedepot that is.

 

There are many materials to choose from. But give an idea of your budget, and what are you planning to put in the box? If you have a $50 budget wood would be the most logical choice. But if you have a couple hundred or so you could look at a wood glass composite or all composite box. If you have considerable experience with metal, you could use aluminum, steel or titanium.