How would one produce low gravity on earth?
Oddly, that's the more practical of those suggestions, because forming a few kilometers of perfect glass by letting it cool while dropping would seem to require a tower impressive in its own right... More relevant, there are QA demands with fiber-optics that don't seem to jive with a "let it hit the ground and throw out the lumpy ones" approach, much less the handling while in full gravity (which is where the issues are).