Abstract: A product includes a metallic and/or ceramic three-dimensional structure having physical characteristics of formation by additive manufacturing. The structure has random porosity within filaments thereof. A method includes printing a structure by extruding an ink thereby creating a printed structure. The ink includes a precursor that is reactive under predefined conditions to form a metallic and/or ceramic material. The method also includes applying the predefined conditions to the printed structure for causing the precursor to react thereby forming a secondary structure of the metallic and/or ceramic material. A method includes applying focused light in a predefined pattern to a composition comprising a precursor that is reactive under influence of the focused light to form a structure of a metallic and/or ceramic material.