I wasn’t entirely sure, but now I’m somewhat convinced: Magnetix magnets can form an infinite chain that won’t break due by its own weight.
(This is not true, however, if you introduce the steel bearing balls between them. That structure collapses pretty quickly if you pull it up like a chain.)
So, this would be a really nice question for What If, IMHO. What if you made a 1 light-year chain of Magnetix? Well, to begin with, we’d need nearly 40 million trillion pieces. That’d cost at least 10 million trillion dollars based on the current prices at Amazon, and would be about 140,000 times the world’s GDP. I’m sure Randall could take this a lot further.