What's the roundest human-made object ever made? One of Einstein's most bizarre predictions led to a pretty dang spherical ball bearing because of course it did.

[also, more on kicking Elon's Nazi bar to the curb]

https://badastronomy.beehiiv.com/p/what-is-the-roundest-human-made-object-also-i-nuked-my-twitter-account

Oh yeah, I know about that. I figured out how to put the niobium coating on those things without affecting the sphericity in any meaningful way. Even a few angstroms of irregularity and the thing could shatter in space and ruin the experiment. Ah the good old days...