Quote Originally Posted by John W
I plan on using a fair amount of stuffing, and I know my volume estimation could be way off. I will have to tune these manually once everything is in place.

Next step is a cardboard mockup to try and get a handle on the angles involved.
Build your mockup to the correct interior dimensions and fill with plastic peanuts to determine the volume. I gave up trying to calculate the volume and took that "empirical" path....