I am making a "structure" out of carbon nanotubes in deep space. This structure can be any shape or design, I just want it big. Big in just one direction is cheating (so no long thin structures), this has to be big in all three dimensions.
Approximately how big can I make this structure before its own mass and gravity becomes strong enough to collapse the structure in on itself and form a sphere?
How big can I go, before gravity makes it a no?
This is not the same as How big can a space ship be before it collapses on itself?, and for these reasons:
This is not a space station, and doesnt require anything to be functional on or in the structure - it is simply a structure made from carbon nanotubes - for all intents and purposes think of it as a work of art. It has no function other than to be appreciated from afar - I just want to know how big it can get.
The question talks about a solid body of rock and it also talks about metal. The accepted answer talks about pre-stressed steel. My structure is made almost exclusively from carbon nanotubes.
The question explicitly rules out a Dyson Sphere, as it should have an internal structure. My question doesn't rule out any shape or design, and it has no requirement for any internal structure (although internal structures are welcome if you want them).
I simply want to know how big I can go with a carbon nanotube structure before its own mass pulls it in on itself. The structure has to be strong enough to hold together for at least a hundred years (ignoring any impacts with astral bodies, asteroids etc).
Just to give you an idea of the scales I am thinking of - I first considered making a cylindrical structure about 50 kpc in diameter (for comparison, our galaxy is about 30 kpc wide).
I am guessing a carbon nanotube structure that was 50 kpc in diameter and 0.2 kpc tall would be too big, have too much mass to maintain its structure and would collapse in on itself. Am I wrong in this assumption? If so, what are my limits?