In the present study, a metal injection molding (MIM) feedstock of aluminum Al 6061 was used as the raw material for extrusion 3D printing and sintering-based AM. A design of experiments methodology was used to systematically analyze the individual and interactive effects of various parameters, such as extrusion temperature, extrusion flow rate multiplier, nozzle printing speed on the green density, and surface roughness. MIM feedstock resulted in shear-thinning behavior as required for extrusion printing. The initial findings revealed a decrease in green density with an increase in nozzle speed, whereas a contrasting trend was observed with a reduction in the extrusion flow rate. A similar trend was observed for the surface roughness measured along the printing direction. Through the application of regression equations and a multi-objective optimization technique, the study achieved the dual objectives of maximizing the green density and minimizing the surface roughness. To comprehensively evaluate the manufactured components, microtomography analysis was conducted on specimens produced under optimized parameters and randomly selected conditions. Subsequently, the specimens underwent debinding and sintering processes to obtain the sintered metal parts. However, sintering results in poor densification, which requires further investigation. The investigations provided valuable insights into optimizing the production of green parts endowed with higher density and better surface characteristics by leveraging extrusion 3D printing of aluminum Al 6061 MIM feedstock.