This deliverable documents the first iteration carried out within the CIRCULOOS Project to design an open and reusable reference architecture for more circular and sustainable supply chains in the manufacturing sector. The main purpose of the proposed Circular Manufacturing Reference Architecture (CMRA) is to contribute with an open reference model that accelerates the creation of innovative solutions to enhance the sustainability, resilience, and circularity of existing manufacturing supply chains as well as to ease, foster and promote the creation of new ones which embrace circularity practices at their very early stages. Tailored for both small to medium-sized manufacturing enterprises (MSMEs) and large manufacturers, major emphasis of the CMRA design is put on enabling the design of effective solutions to reduce waste, streamline resource utilization, and champion sustainability across all facets of the supply chain within intricate manufacturing ecosystems1. Aspects like reusability, modularity, portability and scalability will be driving the design process, always considering security, trust, and privacy preserving aspects as essential enabling pillars of successful designs. The document is structured in two main parts. The first part elaborates on the main principles and abstract design aspects of the CMR. In turn, the second part focuses on the ongoing work towards an open reference implementation of a CMRA based platform which is being carried out in the context of the CIRCULOOS project.