Audio Systems: box dimension, inch subs, air leaks

Question
i need to build a subwoofer box to hold 2 12 inch subs the outsde dimensions are:  Height 14 inches :  Width 29 inches
Depth 14 inches...
i am using 3/4 inch mdf wood with those outside dimensions what sizes do i tell my carpenter to cut the wood each piece?
what is the blueprint dimesions  

Answer
First you must have a box designed for the speakers you are using.  Just any box will not give optimum performance.  For example, have you chosen a vented system or sealed box design and do you have the Q specs on the woofers and have they been fed into the box design equations?

See:
http://www.ajdesigner.com/speaker/index.php

Or, if you are using a design already spec'd out, forgive me.  Such as:

http://www.crutchfield.com/S-ASKBApGBnKu/cgi-bin/prodsearch.asp?search=subwoofer...
or,
http://www.cardomain.com/shoptype/Subwoofer+Enclosures

Your choice of wood is good.  

Since I don't know your design plan, I can only advise you to make sure the cut out holes for the woofers are such that no air leaks around the speaker should be allowed for.  You may have to use a gasket to air seal the mounting when the drivers are properly seated into their mounting holes.

If you are designing from scratch a good carpenter can work with outside dimensions and a sketch drawing of the finished product - and a discussion with you so there is no misunderstanding.  If you have a photo of some box very near to the one you want that would be a good thing to show the carpenter.

Hope this helps.

C

PS: Most woofer driver makers will supply you with box design suggestions upon request - or they may have them on their web sites.  Please check it.