1) You need old tshirts
so that the bottom part of the tshirt is now like a tube
3) Now you're going to fold it like so:
4) Now you're going to cut strips into it, but not all the way. I made mine about 1 1/2 inch wide
5) Now you're going to open it up and you'll have this weird ribcage like thing
6) Cut diagonally to get one long piece of "yarn"
Then just roll it up and use it as you like - I've started plaiting (braiding) mine using three balls of "yarn" to make a rug:
Now I just need some more tshirts to get old and worn!