if you are asking about a string for a recurve or longbow, i used to make them, even made myself a jig from directions i found in a trad bow magazine. however, i haven't made one in 8-9 years as a local bow shop can make me one while i wait. they are quite easy to make, but one has to buy the spools of string (lets say 3 different colors), and the serving string as well. it is satisfying killing stuff with arrows and string you made yourself. good shooting.
