## 6 Summary and Conclusions  
With significant advancements made in both the methods and materials used for electrodeposition, this process forms a crucial technique for metallizing polymeric substrates. While traditional electroplating techniques, such as electroless and electrochemical deposition, have provided valuable insights into polymer-metal adhesion mechanisms, there are still substantial challenges to address, particularly in terms of process efficiency, sustainability, and the quality of metal coatings, their mechanical properties, and failure mechanisms. Recent developments, including the use of environmentally friendly plating methods and novel electroplating additives, offer promising solutions to mitigate the environmental impact and enhance the performance of metal coatings on polymeric substrates. Nickel electrodeposition from a Watts-type bath onto a 3D-printed polymeric substrate is governed by a balance of electrochemical principles, electrolyte composition, and process control, all of which significantly influence the resulting microstructure and mechanical properties of the metal electrodeposit. Additive chemicals, current density, and temperature determine the key mechanical properties, such as hardness, ductility, and internal stress, which in turn affect structural integrity and fatigue life. High internal tensile stress, which is common in certain electrolyte compositions, can reduce the fatigue endurance limit by up to 45%, while compressive stress, achieved by adding saccharin, improves not only the fatigue endurance limit but also the hardness. Surface preparation methods, including the use of silver conductive paint, provide rapid, environmentally friendly alternativesto traditional electroless plating for primary metallization of polymers. Despite recent progress, challenges such as hydrogen embrittlement, sub-surface defects, and location-specific variations in deposition quality remain. We should emphasize that this article is a short review that focuses only on a Watts bath electrolyte formulation and does not comprehensively address the variability and compatibility between other polymeric substrates and electrolyte formulations. We do not quantitatively review the impact of long-term environmental exposure or cyclic loading conditions on the durability of the as-deposited metal parts present in real-world applications. Finally, practical challenges associated with scaling laboratory findings to industrial production, such as process repeatability, economic viability, and environmental compliance are not addressed, representing areas requiring future research. Future research in this field includes closing the gap of knowledge between thin electrodeposited coatings and structural deposits by refining alternative plating methods, improving the uniformity and durability of metal deposits, and exploring new electrolyte formulations that enable high-quality secondary metallization of complex geometries. A greater understanding of the underlying chemical processes at play during electrodeposition, coupled with advancements in real-time monitoring technologies, will be key to furthering the precision and control of the deposition process. By addressing the current limitations and expanding the knowledge base in polymer-electrodeposition interactions, the electroplating industry can leverage new processes to develop advanced structural manufacturing techniques and contribute to the development of more sustainable, high-performance structural applications across automotive, aerospace, and biomedical sectors, while also refining techniques in coating applications. Conceptualization, M.J.M. and G.W.T. ; methodology, M.J.M. and G.W.T. ; formal analysis, G.W.T. ; investigation, G.W.T. ; resources, M.J.M. ; writing--original draft preparation, G.W.T. ; writing--review and editing, M.J.M. ; visualization, G.W.T. ; supervision, M.J.M. ; project administration, M.J.M. ; funding acquisition, M.J.M. All authors have read and agreed to the published version of the manuscript.