False Pearls, Personnal Charms or any other charms you may have here and there.
Take the size of your wrest with a part of the elastic string, but do not pull on the string (make sure, it will not be to tiny, because the pearls will take some place on the string).
Tie one pearl as a starter, to the almost end of your string (make sure a part of the string will be left, so you can tie t to the other end)
Then continue with the pearls, and every 2 or 3 pearls, put a charm.
Tie both ends together, make sure there is no possibility that it will loosen.