Building on The Prydwen

[RED]

I was wondering where on the Prydwen I could build, because hovering over it on the map indicates I can start a settlement there. I also would like to know where I can build in Boston Airport.

[ZS Maeklos]

In the Boston Airport, if you go slightly north from the main gate and face north, off to the left is a section where you can build. There's two (now nonfunctional) doors on the north side of the big building there - those are where you can build.