Depends on the uav, but you could do components for a small one. I've printed legs for drones, and they were small enough that I could have done them in metal. The limiting factor without buying something hideously expensive is more about how much metal you want to have molten at once. For little parts you can use a bunsen burner and a small crucible. If you buy a pro setup, it flash melts the metal for you only at the moment it needs it. But they are expensive.