I’d like to see a pressure vessel made of fibreglass that size… Not happening. Wall thickness in pressure vessels scales
Simple calculator, assuming steel… a 24 km diameter pressure vessel at 15psi is over 13 metres thick steel wall to contain the pressure. checalc.com/calc/vesselThick.html
Just the volume of steel required would be astronomical. You might be able to do this out of a similar mass of fibreglass… But forget launching it from Earth (would have to be made in situ).
And, largely, forget the fantasy renderings of what O’Neill cylinders look like – they are anything but lightweight.