A three-dimensional (3D) metal object manufacturing apparatus is equipped with a movable directed energy source to melt hardened metal drops and form an oxidation layer. A metal support structure can be formed over the oxidation layer, an object feature can be formed over the oxidation layer, or both a metal support structure and an object feature can be formed over oxidation layers located at opposite sides of a metal support structure. The oxidation layers weakly attach the metal support structure to the object feature supported by the metal support structure so the support structure can be easily removed after manufacture of the object is complete.