Horsehair

[Chris B]

You can also drill holes 1/4 " deep enough for the tufts and then drill smaller holes all the way through the wood. Then take linen thread or thicker threads, tie the tuft in the middle, thread a needle, drop it through and pull it tight into the holes with glue present. That way each tuft of hair is extremely tight in the box and the strings passing through the entire crest box will keep them from pulling out very easily.