This is my most basic line of enclosures. Literally just a square enclosure made out of 3/4" MDF material. No carpet or wiring. This one will be for a single subwoofer and downfiring, meaning that it has legs on three sides forcing all the sound pressure out one side. Helps for better sound in smaller cabs like a pickup truck. Also protects the subwoofer from theives seeing it and other cargo damaging it.

You can choose the size of subwoofer, and also choose the final airspace in the drop down menus. 

All downfiring enclosures made with 2.5-3" of space between floor and woofer