This is a very difficult question to answer because it is dependent on the exact tooling that you used and the material used. If you use the correct tooling with very high-quality material, your whistle should last as long as any other carving. A few years; decades or a lifetime in some cases. If you make a wooden whistle that has less than .010″ remaining thickness, it will begin to break down in about 4 years after being carved. I would recommend taking your whistle in for an annual tune-up to be sure that it still works properly.