A good rule of thumb is 2 hours, but it will vary. We're giving you a range of temperatures, though you definitely want to keep your smoker on the low side. Even so, the time will depend on how steady the heat remains in your smoker and the size of the noodles. Keep in mind that you want to make smoked macaroni and cheese alone or when cooking meat at lower temperatures. Medium heat and above won't give great results.