If you have an old t-shirt that is unwearable you may be able to up-cycle it into a new necklace.
Cut the shirt under the arm area as well as the hem running along the bottom of the shirt.
Beginning at the bottom of the shirt and working your way up, cut 1-inch strips to make loops. You can either cut all the way up or leave about an inch at the top to keep all the loops together.
Vary the width of your strips based on your desired necklace thickness. Keep the width small for lots of loops or larger for fewer. You can even cut a variety of widths for a less-uniform texture.
Stretch out the loops you just made so the cotton curls in on itself and forms long tubes.
Double up each tube, matching up the seams at one end.
If you break a loop at the seam while you're stretching it out, just tie it back together with a simple knot and trim the excess.
Group all of your tubes by size, keeping the seams together at one end.
Gather them all together, with the longest tubes on the bottom and the shortest on the top, but save one.
Cut the tube you saved in half to make it a long string. Tie the string in a knot near one end of the section of seams. Tightly wrap the string around all of the seams to cover them. Be careful not to get the tubes twisted or tangled as you're wrapping.
When everything is smooth and covered push the end of the fabric up under the rest of the fabric to hide the end.