[P11GT]

When building a box, theres lots to consder, the overall size for a start, the design (shape) you want it, the material, and the most important, the internal volume. Do you have the spec of the sub in question? Post up the make and model number, so i can have a look for you. Maybe i could design one for you, but i'll need info such as recommended internal volume(s), sub displacement, available height, width, depth oh and port length and diameter.

Heres a picture of mine that i built over 3 years ago and its still going strong. It houses a JL Audio 12W6 and is 2.0 CuFt and has a port length of 9 inches dia of 3 inches. The design of it is based on the MTX V80, a 8 inch sub which packs a hell of a punch and rated at 400 watts, particially to do with the design of the box. It has no side which have the same length, therefore the sound does not bounce and cancel itself out.