adding and moving individual atoms is done, with an atomic force microscope. Up to now, only tiny drawings have been made, with no other goal than showing off. The semiconductor industry thinks at it, since presently gate oxides are a dozen atoms thin and transistor gates are 50 atoms long - but then, a circuit needs billions of transistors.
Processing a macroscopic piece of metal that way is to my knowledge still out of reach. Unless someone had an idea, built a massively parallel machine, or whatever. But in nano-scale it looks feasible, especially at one flat face.
Getting a piece of metal blank is quite difficult, because most metals are reactive, and the best vacuum is full of residual gas. In very deep vacuum, you can hope that a noble metal surface consists mainly of the metal atoms for an hour or so. In air, reactions and adsorption happen immediately. You would want to coat a metal to avoid undesired reactions (corrosion) or to know better what elements are below the few atomic layers of adsorbed gas.