Abstract: Three dimensional printed objects having surface coatings, such as a hydrophobic coating or metalized surface, 3D printed substrates having an outer surface that can be tuned by application of such a coating, and methods for the fabrication of such objects and substrates are described. A surface initiator is incorporated into the 3D substrate during layer-by-layer printing, and the surface coated by surface-initiated atom transfer radical polymerization (SI-ATRP).