Step 1: Cut Your Bamboo
once you have your small piece of bamboo,use the flat end of your skewer to clean out the soft flakey inside of the bamboo.
Step 2: Add the String.
tie a permanent knot in one end of the string,making sure that the knot wont fit through the bamboo,and push the other end through.
now tie a loose not on this end.
you are now essentially done,you can tie it onto your keys or add a keyring,whatever.
but you don't have to stop here,you can also add carvings paint it,burn designs into it(see pic)whatever you want,it's your keychain,make it say something about you.
I used an old butter knife that I heated up on the stove to burn a gungnir into mine,and tie it onto my car key without a keyring.