## 6 Implications  
The magnesium particles mixed well with the polymer matrix, and the PLA and magnesium particles did not react chemically. There were no significant differences in the crystallization of the Mg-loaded samples. The cross-sectional pictures of the filaments demonstrate an even distribution of magnesium particles up to a concentration of 15% WE43. Later, the distribution became uneven, pushing the magnesium granules to the edges of the filament cross-section. Additionally, the printing ability of the pores near the magnesium particles changed when the WE43 level increased from 15% to 20%. The low-cost FDM 3D printer demonstrated good printing performance with 5% and 10% WE43 composite filaments [160]. Consequently, these filaments have the potential to create composite biomaterials for bone implant printing. Further studies are needed to assess the biological and mechanical characteristics of these composites. Adding useful functions to ZnO stopped PLA from breaking down and allowed for biocomposites that were more stable at high temperatures to be made. As a bone substitute, 3D-printed porous scaffolds had an elastic modulus that was similar to that of real bone tissue. The amount of ZnO affected all the properties studied, but more time in the plasma did not. The samples that contained 10% ZnOMA had an improved relationship between cellular mineralization and cell longevity, which makes them especially promising for biomedical uses [161]. Looking at the results, examiners saw that above a CuNP concentration of 1%, the virus-killing effect starts to work well. The melting point of the material (Tg) went up as more CuNPs were added, which let us see how the extrusion and additive manufacturing processes affected the results. It became more crystallized after CuNPs were added, which shows that the nanometric particles in this material helped crystallization begin. Thermal analyses with TG and DSC were used to observe this type of activity. In terms \begin{table}
\begin{tabular}{c c c c} \hline
**Sl.No** & **Metal Infill** & **Applications** & **Ref.** \\ \hline
1. & Mg & Bone Tissue Engineering Scaffolds & [141] \\ \hline
2. & Mg & 3D-Printable PLA/Mg Composite Filaments & [46] \\ \hline
3. & Zn & Antibacterial Orthopedic Implants & [142] \\ \hline
4. & Zn & Direct Ink Writing (DIW) for Scaffold Fabrication & [143] \\ \hline
5. & Zn & Surgical Tools, Orthopedic Implants, Dental Applications & [144] \\ \hline
6. & Cu & Food Packaging Materials & [145] \\ \hline
7. & Cu & LED Housings & [146] \\ \hline
8. & Bronze & Electromagnetic and Magnetic Applications, & [147] \\ \hline
9. & Bronze & Fit and Form Testing & [148] \\ \hline
10. & Bronze & Art, Sculpture, and Jewelry & [149] \\ \hline
11. & Brass & Used in Investment Casting Workflows & [150] \\ \hline
12 & Ti & Custom Gadgets, Phone Cases, Eyewear Frames & [151] \\ \hline
13. & Fe & Sensing, and Magnetic Devices. & [152] \\ \hline
14. & Fe & Biomedical Engineering & [153] \\ \hline
15. & Ag & Low-Cost Antimicrobial Surgery Equipment & [154] \\ \hline
16. & Co & Supercapacitors & [155] \\ \hline
17. & Co & Surface Modification and Functional Coatings & [156] \\ \hline
18. & Ni & Porous Structures & [157] \\ \hline
19. & Ni & Catalysis & [158] \\ \hline
20. & Ni & Electromagnetic Wave Absorption & [159] \\ \hline \end{tabular}
\end{table} 
Table 2: Applications of different metal infill in PLA biocomposites. of mechanical and thermal properties, the nanocomposites were not as effective as pure PLA [162]. Adding bronze particles to the PLA material strengthened it, which improved its tribological properties. The wear depth significantly decreased compared to previous reports. Even so, the friction stayed the same because the polymer composite matrix was full of rigid particles [75]. In the end, this study looked at the mechanical and physical properties of PLA/brass composites as well as the strength of 3D-printed parts created with FDM.