I haven't used a metal key ring for decades. I cut off a few inches
from a leather shoelace, string my keys on it, match the ends and tie
a single knot. I've found it a great deal more reliable than any key
ring or chain. Lasts several years, then I cut a few more inches off
the shoelace. I think the leather shoelaces I bought in 1973 are
almost used up and I'm gonna have to buy a new pair, dang it.

Only downside is that taking a key off (for example for a mechanic) is
a pain, because the knot gets pretty tight after a while. If I had to
do that daily, I would not like my solution. In fact I probably do it
half a dozen times a year, which I can manage.

Edward