custom cabinet basic concept 
Metrics:

* Width:  99" at back.
* Width:  73" in front, then sloped to match bulkhead.
* Depth:  19-3/4.  Matches bulkhead in ceiling.
* Height:  "counter height".  Variable.

* Left Section:  26"
  * 2 shelves, open lower area for subwoofer.
  * Top shelf 5", Second shelf 9".
  * Bottom area at least 17", up to 22".  Covered?

* Right Section:  26"
  * Triangular section, a = 19.75", b = 26", c = 32.7", Aa = 37.2`
  * Matching left-side openings:  5", 9"
  * Bottom area split into two shelves.  Covered?

* Center Section:  47"
  * Full width drawer.  Does not need to match height top shelf on sides.
  * Cabinet doors, 2 bins on rails?
main cabinet









perspective:

main cabinet
left
bottom