Stray String Ends
They can rattle against neck or body
Here's another really easy one. Those loose string ends can rattle against the top of a classical guitar:
It's amazing how loud they can be! Just clip them short so they can't touch the top, and you're done!
If I hear a buzz that appears to come from the peghead, I'll immediately snip the string ends if they look anything like this:
Not surprisingly, coiled loose string ends can easily rattle and buzz, sometimes intermittently, sometimes sympathetically with certain notes.
Every so often I encounter one like this:
Even a tiny short end can be positioned just right to make a special little noise.