Before we can get into explaining phasors and creating actual parts we have to break everything down into constituent components. Below is an example of breaking down parts of the whole into individual components. I've broken up the base engineering hull, into three separate parts, for the sake of this discussion. Note; though the center section is not a perfect cylinder it will suffice for this discussion. If we were going to machine this part we would use measurements directly from the profile.
We will come back later and add the addition cylinders inside the deflector cowl as referenced by Charles Casimiro's prints and other data.