I suspect without ISRU production of bulk orbit sheet metal, the most feasible solution is to repurpose rockets in their whole.

Building a station this large is gonna be costly even within the cargo hold of starship. But six of them, gutted of insides as welded end to end could provide the vast majority of the bulk mass.

This assume rather sophisticated orbital welding and object manipulation; but its feasible we could do it with robots.

I never understand why the rotating station concepts seem to all have rigid tethers, either in the form of a central boom or a rigid circular structure. It would seem like you could get a much larger diameter, so less rotational velocity and more comfort, by attaching rigid, or inflatable in this case, structures with a tether. Compressive loads are non existent, you just need to resist tensile loads.

Maybe I'll go ask the AI.

Anything that can be inflated can usually be deflated.