Glenn, Aimless,
Shoelaces? (a pair of them????)
I think I broke one when I was 19, but not since. Now check my gear before I leave. I believe a piece of my food hanging cord would suffice to get home.

One time I was on a design team and they were trying to figure out to make a machine self testing. I said "All of the self test circuits complicate the design, create potential failures, and anyway this stuff is all ruggedized. I suggest instead that we find a way to test something with a higher failure rate, like the on/off switch." The team agreed with me and we dropped it.