What I endedup with for the dimensions on the 2Pi towers is 14 1/2" x 16 1/2" x 46" outside dimensions (ya I know I goofed). I am using 3/4" birch plywood. I have 2x2 (1 1/2" x 1 1/2") in all four corners vertical from top to bottom where plywood sides and front/back meet, and top and bottom where top/bottom and front/sides meet (I saw this done by another person who built the 2Pi). I will be bracing with 2x2 also. My port came out about 1/8 too big at 4 3/4" (thats a pretty big hole) about 1/8 bigger that I tried to cut it but my sabre saw got away from me a bit. I would like to have used a hole saw for the port hole but could not find one that big. Good thing I decided to put the port hole in the back side. I think if it will help I can put something inside the port hole if I need to to make it a bit smaller.

Given all the 2x2 I have inside it will take up some volume so maybe the extra large box will not be a problem.

As far as the box size being a bit larger than it should be... maybe I will be O.K. with the port being 4 3/4" instead of 4 5/8" as specified.

What do you think Wayne?