## 5 Conclusions  
The integrated architecture presented in the paper is in line with others reported in the literature [65, 66], where open 3D printing resources are used to achieve customized environments that are cost effective and have customized functionalities.  
The proposed service-oriented architectures (SOA) [77] could be defined as a pseudo Printing-as-a-Service (PaaS) architecture, because a part of the printing process (configuration and motion control code generation) is executed in the cloud as an external service, but the printing is performed locally. The framework focuses on business in the port and maritime-related economy and commercial activity business scenarios, which are not primarily oriented to the manufacture of parts and products.  
Survey data about types and amount of plastic waste (summarized in Table 1) have shown that there is a lot of plastic to be recycled, though there are many types of plastic waste in many types of products. Effort should be made not only to increase the total amount of plastic waste that is recycled but also to try to recycle effectively as many plastic types as possible. The alternative is that the recycling effort could be put into just one type of plastic, and the others could be disregarded, with no attempt at recycling. However, this would not follow Circular Economy principles. That is why this paper considers it important to facilitate, as much as possible, the inclusion of a greater range of plastics in the recycling effort in order to not only recover as many different types of wastes as possible but also offer the end-user a wide variety of recycled material choices to cover their needs.  
The paper answers the question about how current 3D printing technology can adapt to and work feasibly with filament made from recycled waste plastic that has a wide range of types and qualities, which is common in maritime and ocean port settings. It does so by proposing a new strategy based not on trying to generate filaments with \"standard characteristics\" but rather on allowing an unlimited variability of qualities or parameters. To do this, 3D printing applications should be able to work with an unlimited variability of plastic qualities and no regular characteristics in a transparent (easy) way for non-expert users (not experts in materials or 3D printing technology), where the technology automatically adapts to any plastic. The presented framework implements this new strategy and has been tested in a prototype implementation. It has been proven that the number of operations and amount of time required to perform a print job are much lower in the case of the integrated 3D printing environment.  
Conceptualization, J.G. and B.L.; methodology, J.G., D.S. and B.L.; software, J.G., D.S. and B.P.; validation, J.G. and B.L.; formal analysis, J.G., D.S., B.P. and B.L.; investigation, J.G. and B.L.; resources, D.S. and B.P.; data curation, J.G. and D.S.; writing--original draft preparation, J.G. and B.L.; writing--review and editing, J.G., D.S. and B.P.; funding acquisition, J.G. and B.L. All authors have read and agreed to the published version of the manuscript.  
This research was partially funded by the European Regional Development Fund (ERDF): Interreg Atlantic Area programme, grant number EAPA_117/2018\" and The APC was funded by the ERDF: Interreg Atlantic Area programme.  
Not applicable.  
**Acknowledgments:** The authors express sincere gratitude to project stakeholders of the Vigo node (companies, research institutions and port management) for their valuable data and their support.  
**Conflicts of Interest:** The authors declare no conflict of interest.