I started with a cardboard template and eventually came up with this
Then I worked out how to mount my visors in it, which are pretty important to me. They will only lay flat and fold down in ONE position, which you have to find carefully. As you may know, they are mounted to the factory roof at an angle and it takes some patience to get them to cooperate on a flat surface.
Then I added some edges and a center seperation to keep things organized up there.
Then I carefully screwed it to the inner sheetmetal of the roof, expirementing with different lengths of screws to bite through the inner sheet metal and not through the roof.
And there you have it
Mine will be carpeted soon, and for now I skipped adding any powered things like CB, powerpoint, etc. But I may someday. I just love that I finally got this project done after thinking about it for years.