All you need are some beads including one to hang as a pendant in the center, 4-5 lengths of fiber(short necklaces take about 3 yards, long ones take 4), a pair of those cone shaped jewelry findings used at the ends of multi-strand necklaces, and a clasp.
First you slip the pendant to the center of one of the strands. Tie a knot to secure it. Then you just go up one side tying all the fibers into a knot and then stringing a bead on one fiber. Repeat using your own pattern and variation. If the necklace is long enough to slip over your head, you can just tie the 2 ends together and let the fibers hang down the back.