3D printing (also referred to as additive manufacturing) offers a huge potential to increase the sustainability of after sales service supply chains for assets like defence systems or airplanes. Instead of stocking a large variety of slow moving spare parts with high demand uncertainty, these parts may be printed on demand, or repaired downstream the supply chain using printed components. This project aims to identify how 3D printing can be deployed, for which types of parts and in which part of the assets? life cycle. We will show, using mathematical models, applied in case studies, the sustainability impact on design and planning of service supply chains. We expect lower system downtime and lower inventory levels of spare parts, leading to lower holding costs and strongly reduced numbers of scrapped components. Sustainability is further improved by de-stressing the supply chain: less emergency supplies in case of stock outs are needed, which typically require air transportation. Also, forward flows of specific parts are replaced by distribution of a limited diversity of raw materials that can be sourced at many locations. In work package (WP) 1, we aim to identify the types of parts for which 3D printing may be applied, and to study its impact on failure behaviour and material costs. WP2 focuses on the design of the after sales service supply chains, including the optimal installation of resources for system upkeep. WP3 focuses on the tactical planning and the impact on spare parts inventories, obsolescence and (emergency) transportation of spares.