If you get to the point of ring worlds or encasing entire star systems in a rotating sphere you're to the point that in fiction you can lampshade how all of this was built with vague science. If you try to go into too much in-world you're either going to have to study the topic heavily to the point you might as well get a degree in various fields of engineering and just go work at NASA, or everything will become so top-heavy the story collapses on itself and it becomes a mess.

There's maybe only so far you can probably get by trying to construct such a far-future from a contemporary standpoint. Not saying it's impossible but the scope is pretty beyond our current engineering theories and I feel that trying to apply what we know now may not be the most approachable thing. Best to simply say it is and go about your way.