So I ran into an interesting situation, and I have to ask: Is there any way to build a ringworld in a system other than having a planet there? I found no ship system which could take material from the empire bank, which seems a strange oversight. Is it possible to build a ship large enough to contain all of the materials to build a ringworld? You can't use a station because there is no way (as far as I know) to move a station.
The situation: Small map (25 stars) starting with advanced technology, 1vs1 with me and a friend. About 2 hours in, all planets have been destroyed and the only thing left are three heavily defended ringworlds and a few size 1,000,000 ships. We have no way to expand at that point. I've already mined out every asteroid in the galaxy with jump-capable autominers which refine and export the metals as they mine and run on buzzard ramscoops with zero net fuel consumption so they can go forever. I have several trillion metal in the bank. I found out that mines on a ringworld somehow continue to generate metal even though there is no ore... bug?
In fact mines on planets will still make metal long after the ore is gone too, which makes me wonder what ore is actually there for.
I'm going to go test it out and see if you can make a ship that large. Even if you can, filling it will be a pain because you can't pull stuff from the bank on a ship or station.