Despite its potential to revolutionize spare parts production, the widespread adoption of Metal Additive Manufacturing (MAM) remains limited, primarily due to the lack of comprehensive cost estimation models that fully capture the intricacies of the manufacturing process chain. This study develops a process-based cost estimation model that systematically evaluates design, material, manufacturing, post-processing, and qualification costs through detailed process mapping and cost allocation. The process-based analysis demonstrates that manufacturing costs constitute the largest portion of total costs across all components, with sintering costs remaining constant regardless of component size. Post-processing costs exhibit substantial variation based on component complexity, while qualification costs reflect application-specific requirements. The developed model provides quantitative insights for supply chain managers in optimizing spare parts production strategies and resource allocation. This study advances the understanding of MAM economics and offers practical implications for organizations seeking to integrate additive manufacturing in their spare parts supply chain operations.