In modern era, electronic devices have enhanced the quality level of human lives; however, they could act as electromagnetic radiation emitters, perturbing the performance of other surrounding electronic devices, and even worse, having a negative impact on biological/living species. To address this issue, a range of promising and versatile electromagnetic interference (EMI) shields have been developed to mitigate the adverse effects of electromagnetic noises. Nevertheless, there is still much room left for further advancement in choice of materials and manufacturing technologies for developing cost-effective, flexible, high-performance EMI shields. From a materials design perspective, poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), which is known as the superstar of intrinsically conductive polymers, is a perfect candidate for developing advanced high-performance EMI shields. PEDOT:PSS possesses many unique properties, such as good film-forming ability, exceptional electrical conductivity, flexibility, and water processability. However, fabrication of PEDOT:PSS or its nanocomposites structures mainly relies on conventional manufacturing technologies such as vacuum-assisted filtration, spin-coating, and spray coating with limitations and challenges in terms of macro-scale design. In this research study, we focused on extrusion 3D printing of various PEDOT:PSS inks (e.g., pure and acid-treated PEDOT:PSS hydrogels along with their nanocomposites with MXene or large flake graphene oxide) as a promising strategy for macro-scale engineering of patterned shields. Our method offers customization, reduction in material waste, and rapid production compared to conventional manufacturing technologies. We leveraged extrusion 3D printing technology to develop a novel class of micrometer-thick EMI shields that present exceptional EMI shielding effectiveness, outstanding flexibility, and minimum production cost.