Take the old used wound string, and unwind the winding. Discard the core. You only need an inch or so of the winding.

Loop the winding, which is a fine wire, around the new guitar string, with a loop about 2 or 3 times the diameter of the new string. Twist the ends a few times so it stays on. It's loose. When the guitar string vibrates, the loop rattles on there making a nifty effect.

This makes a guitar sound like a sitar. I discovered this back when the Beatles were making money off their India experiences and everybody was going bananas over the sitar sound. I bought a Ravi Shankar album and listened to it many times. Might still have it...

Add a short piece of fine thread, tied around the loop's twist, and lead that over to the bridge where you tie it around the peg or the knot, whichever you have there. This holds the loop from wandering off along the string, and the stiffness of the thread holds it from moving right up next to the bridge where it would do nothing.

I haven't done this for many years, I was a teenager and I'm 70+ now. But I don't think physics has changed...