Once I have the Avionic system working from an electronics perpective, them I move into building a case, circuit board, and base to house everything> I try to make each system look as much like a real system from a real aircraft as possible, though I do make some compromises for funcitonality. In the case of the Audio Panel, the buttons that i aquired have LED's build right in their center. The real KMA30 has their LED indicators offset, with works printer on their buttons. The Audio Panel also has teh Approach Lights for Outer, Middle, and Inner indicators, which hve to be included as well. I deisgn the PCB using diptrace while making sure its 3d footprint fits inside my case design. Both are augmented as needed until I am satisfied, then the PCB is ordered.