## 1 Introduction  
Additive Manufacturing (AM) is a group of layer-by-layer manufacturing processes that makes it possible to simplify the production process and take advantage of an increased level of freedom in the design. The workflow for an additively manufactured component starts from the conception of a 3D representation of a component that subsequently enters the production process. The production process of AM components consists of repeating production steps, including a file conversion from Computer Aided Design (CAD) to Stereolithography (STL) files, machine setup, printing, removal, and usually post-processing. AM is often classified into seven process categories and numerous sub-processes, encompassing different approaches to generate 3D objects [1]. The first AM process which is called Stereolithography, applying a laser to cure light-sensitive resins, was developed in the 1980s. Since then, many other processes have been developed, ranging from melting of titanium alloys using Selective Laser Melting to jetting of binder droplets on gypsum particles applying binder jetting [2]. AM is shifting continuously from prototyping for visualization purposes to a production of end-use components, leading to a growing number of industrial applications (e.g., dental and automobile sectors) and may have the potential to disruptively change established markets [3; 4]. It is particularly useful for the low-volume production of highly complex components, which require many production steps in traditional manufacturing. Thus, it makes tooling costs redundant and usesmaterials in a more efficient manner, resulting in less waste material. Therefore, AM can be of major advantage in supply chain networks. Part-on-demand production and customization of additively manufactured components and a high degree of digitalization lead to severe impacts on supply chains and potential future distribution scenarios [5]. Future forecasts regarding AM processes indicate that they will be widely applied, that the quality of components is expected to improve, and that enhanced mechanical properties could result in the adoption of AM components even in safety-critical sectors such as airplane production [6]. However, several challenges including the control of complex material-dependent process parameter interactions to ensure repeatable high part quality, fluctuations in mechanical properties (e.g., ultimate tensile strength) and surface roughnesses caused by varying placements and orientations of printed components during fabrication, and insufficient process standardizations need to be overcome to classify AM as a mature production technology [7; 8; 9; 10; 11]. Due to the continuous evolution of AM processes, there is an incentive to reconsider the existing supply chain models, which leads to modified manufacturing and distribution scenarios [12; 13; 14; 15]. Two major manufacturing models have been proposed, centralized and decentralized manufacturing. Centralized manufacturing distributes products from a single central manufacturing site to customers. Decentralized and in particular distributed manufacturing are realized by setting up a network of smaller manufacturing sites (possibly even at home) distributed over a geographical entity. The models differ in customer responsiveness, supply chain network reliability, transportation and model implementation costs. Main spare part importance criteria are the stock-out-cost, lead time, and usage value [16]. Companies adopt AM processes in their supply chains because it has the ability to result in decreased total variable costs. AM-based supply chains present a substantial change in the cost structure of a manufactured component. While in conventional manufacturing-based supply chains the majority of the cost of a component is traced back to logistical costs; the bulk of the cost of an additively manufactured component is direct manufacturing costs [17].