## 4 Conclusions  
This study presents an overview of the main mechanical characterization tests performed on debinded and sintered samples fabricated by means of an innovative metal-polymer feedstock on a low-cost ME machine. Specimens for mechanical characterization were printed using the optimal combination of process parameters for obtaining the highest bulk density compared with that of the monolithic material.  
Tensile specimens printed via the ME technique exhibited lower values of yield strength and UTS compared to those of the monolithic material. In particular, the yielding behavior exhibited the worst load values. The compression action on the specimens enhanced the average stress value in direct proportion to the increase in displacement. The bending samples exhibited no cracks or deformations on the surface subjected to a tension load. An XRD analysis showed the abnormal presence of \(\delta\)-ferrite in the austenitic matrix, which may explain the brittleness of the metal specimens observed during the Charpy impact tests. Both Rockwell B and Vickers hardness tests verified the homogeneous behavior of the material along the growth direction of the layers. In general, the conducted experiments indicated that the ME 316L samples had poorer mechanical performances compared to those of monolithic materials. However, all the tests performed demonstrated the excellent repeatability of this AM process.  
Metal extrusion is a prospective cost-effective technique that avoids powder handling and reduces the carbon footprint compared to traditional metal additive manufacturing technologies. Despite the promising advantages, the considerable presence of porosity and the necessary improvement of the mechanical properties narrow the industrial applications of this technique to non-critical metallic parts with high added value, including tanks for dyeing machines and pipelines for the chemical industry due to the high resistance to corrosion. The biocompatibility of the material ensures its use for food and medical applications, and the possibility of producing complex-shaped parts extends its application to heat exchangers and heat sinks.  
Figure 8: Rockwell B Hardness (**left**) and Vickers hardness (**right**) values in their relative positions within the sample.  
**Author Contributions:** Conceptualization M.C., M.Q., G.D.; methodology, M.C., M.Q., G.D.; formal analysis M.C., M.Q.; data curation, M.C., M.Q.; writing--original draft preparation M.C., M.Q.; writing--review and editing, M.C., M.Q., G.D., C.G.; supervision, G.D., C.G.M. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research received no external funding.  
**Institutional Review Board Statement:** Not applicable.  
**Data Availability Statement:** The data presented in this study are available on request from the corresponding author.  
**Acknowledgments:** This paper is part of a research activity carried out within a Ph.D. fellowship titled \"Development of innovative powders, also from waste and/or recycled materials, to be used in the production of components using additive technologies\" and is funded by ENEA (the Italian National Agency for New Technologies, Energy and Sustainable Economic Development) in collaboration with Region Lombardy.  
**Conflicts of Interest:** The authors declare no conflict of interest.