User blog comment:Unownshipper/Metallurgists Wanted: Rapture's Natural Resources/@comment-75.36.142.53-20140810065007/@comment-3967731-20140810094848

I'm willing to bet that for a person to drop everything and move to an underwater city (essentially a very deep fallout bunker), the citizens of Rapture must've really been buying into the fear of Nuclear Apocalypse that so proliferated the era.

With that in mind, they'd assume that the Surface World would eventually wipe itself out, so self-sufficiency is at best a goal and at worst the only option for these people, so it's something they'd strive for.

As for the sorts of composite materials you're discussing, you're right about plastic taking off and of course there already was bakelite, but have you heard of mineral wool? It has the same thermal resistant properties of fiberglass, and it's a natural product of molten rock. It can also be used in filtration, soundproofing, and hydroponics.