For reasons I want to make a very simple pendant attachment. The pendant is basically just a small tube.
My idea is to make a very simple spring type that would hold by tension alone (just supported by a drop or two of superglue or something like that).

Now my question is: What can I use for that? Obviously I want some kind of spring steel, so just taking a piece of copper wire or another piece of cord or whatever is out of the question, I just have no idea what to use here. An actual spring from something would be preferable, but I have no idea where I could scavenge it from.
Any ideas?