In this talk, I will discuss recent advances in the development of robotic printers, and the synthesis and 3D printing of different metal and metal oxide material inks on rigid and flexible substrates. Also, I will report the development of highly mesoporous foam structures utilizing continuous-flow direct writing. Special emphasis is placed on studying environmentally-friendly inks for enhancing the sustainability of manufacturing and reducing the use of harmful solvents. The directly written structures’ properties are investigated, after exposure to different curing/sintering mild conditions such as UV radiation, and/or low temperatures (usually below 150 oC). Understanding the resulting properties, with respect to processing conditions, is necessary to control the mechanical, electrical, and microstructural characteristics of the printed structures. In particular, I will discuss some of our recent projects including the investigation of the optical, electron transport, mechanical, microstructural, and surface chemistry properties of Ag micro-patterned contacts, TiO2-based films and printed foams, and ZnO-based photosensitive structures.