## 6 Implications
An experiment looked at how different printing settings (layer height, printing speed) and materials affected different mechanical properties. These properties included yield strength, ultimate tensile strength, bending strength, bending modulus, compression strength, compression modulus, and energy absorption. The outcomes indicated that printing parameters and the composition had a big effect on the mechanical characteristics of the PLA/brass composites [163]. Some combinations of printing parameters and specimens made of 15% brass gave the best results for numerous mechanical characteristics. However, examiners found that the optimal mix for impact characteristics was 80 wt. % brass. The layer height and printing speed significantly influenced the Young's modulus. On the other hand, the composition had the most significant effects on the impact characteristics. These results show how important it is to choose the right printing settings and materials to obtain the best mechanical properties from 3D-printed PLA/brass composites [164]. According to the results, heat treatment could change how the titanium particles are distributed in the PLA matrix, but it does not always make the material stronger when it comes to tensile strength. The dispersed arrangement of particles seen in most specimens indicates that holding at higher temperatures for longer periods of time might cause particles to stick together or additional structural modifications that make the material weaker [165]. The influence of the printing settings on the tensile strength of PLA and PLA/aluminum was evaluated [166]. Three printing settings were changed for the study: the rate of printing (mm/s), the number of shells, and the layer thickness (mm). Taguchi's DOE was used to print 18 samples, and the tensile test was performed on all of them. The result indicates that PLA has a tensile strength value that is about 20% higher than PLA/aluminum. The reason is that the printed portion of PLA and aluminum was not always the same, which made the bond and structure weak. Both materials' tensile strength is most affected by the number of shells, according to the ANOVA test. Therefore, examiners determined that the number of shells increases the tensile strength of the FDM-made PLA and PLA/aluminum composite. New recycled iron/PLA composites could be useful in construction, biomedical, and auto companies, where sustainability and low costs are important [167]. This is due to their superior energy absorption and compression capabilities. To improve the mechanical characteristics of these composites even more, future research could investigate how the iron particles are distributed within the polymer and how that affects its compressive strength and power absorption. It could also investigate new material formulations using different fillers, reused iron, and biodegradable polymers. The goal is to create long-lasting 3D-printable composites from recycled and eco-friendly materials that have better properties for a wider range of end-uses [168]. It was stated in some Life-Cycle Analysis (LCA) studies that the PLA-based composites end up in composting or landfills after their End-of-Life (EoL). The greenhouse gas emissions in each stage of the utilization of PLA were analyzed, including the acquisition and conversion of the feedstocks, manufacturing of PLA biocomposites, their applications, and finally EoL conditions. Conversion from the feedstock was evaluated to be most energy intensive process in the lifecycle of PLA. If the conversion process was optimized to consume low energy, then PLA could be a potential low carbon material even at its EoL [169; 170]. Some other studies have stated that metal ingredients and polymeric compounds could kill _E. coli_ and _Listeria monocytogenes_ bacteria during all stages of industrial production. At a concentration of 2%, the additive R148 demonstrates its maximum effectiveness in killing microbes on surfaces, indicating its potential for use in medicine [171].