OK.. getting down to crunch time....I figured out the FINAL cut list using 2 sheets of 5'x5' baltic birch. Internal volume comes out to 11.37..thats seems to be the largest I can make the box with 2 sheets. I still need to subtract the port area from that total....so the question is..
1. How do I calculate that?
2. How do I calculate what port length to even use with this size box?
3. How does this look so far? I feel like I am going to end up on the small side of a true LLT

The things I do no is that the internal dimensions are 18.5" x29.5"x36" (39 inches overall but I am subtracting 3 inch's based on 2 end pieces and 2 braces...each being .75" thick)