>One could, I suppose, theoretically loft a billion-zillion tiny parts
>and put them together in orbit, but it would be heinously inefficient
>and the possibility of things going messily wrong during assembly are
>pretty high; plus it doesn't fit in with the world's pulp action
>ethos. Bolting together modules in orbit swashes no bucklers.

Spoken like someone who's never tried docking in Kerbal Space Program.

Seriously, it seems like the KSP aesthetic is what you're going for. You should give it a try.