This was brought up before but if you have a string of smaller Xmas lights that no longer work cut the plug and light sockets off and then cut the wire in 6"or 7" lengths,  take a wire stripper tool and strip the insulation off the wires, leaving  1/2" or so of insulation in the middle to hold the thin wires together until needed, you'll end up having a life time supply of nice fine copper wire to rib your flies with. Thanks & Merry Xmas