How Big of a Hole Do You Cut for a 12 Inch Subwoofer?
Subwoofer boxes come in a wide variety of styles. The sealed enclosure is the most widely used and the easiest to construct. You would need a 2 inch wide hole for each of your 12 inch subwoofers. You can find more information here: http://www.ehow.com/how_4073_build-subwoofer-box.html