Background - Consumer individualisation is a growing challenge in the fashion industry, yet it is also an area of great potential as well as a way to dampen over-consumption. The potential lays in how fashion brands can find ways to steer consumption towards a circular economy and utilise their platform to create meaningful connections with its consumers. Today the fashion industry is looking at options to the traditional take-make-dispose model where non-renewable resources are used at an ever-increasing rate. The Swedish fashion retailer Monki together with Re:textile decided to investigate if servitization could turn the above mentioned linear model into a more sustainable, circular model. They set out to develop an in-store concept where customers could customise their garments instantaneously and this formed the basis of a project brief and a Business Model Canvas which both served as the foundation and starting point of the presented research.   Purpose - The purpose of the research is to develop and test a product extension service business model that utilises a direct to garment printer to mass customise jeans in-store. The said purpose is divided into three perspectives: the design-, service provider - and customer perspective , covering four cornerstones of the Business Model Canvas. The different perspectives with their separate, but related, research questions will be unified again in the conclusion.   Methodology - To fulfill the purpose, the thesis research is relying on abductive reasoning through systematic combining, while implementing a mixed methods approach. Systematic combining works well in extensive and diversified research where the researchers shift from one type of research activity to another in a quest to match empirical observations with theory, thus, the ultimate objective of systematic combining is matching theory with reality until both come close enough to form a functional outcome. Throughout the study, both qualitative and quantitative studies are conducted through action research, a customer case study as well as experimental research in order to fulfill the purpose of the thesis.   Findings and Discussion - The conclusions and recommendations that are presented in the form of an updated Business Model Canvas all derive from the research conducted incorporating the three perspectives that have guided the thesis through all of its stages namely the design, service provider and customer perspective. A product service extension business model is proposed as a solution to the project brief that serves as a foundation for the research. The results of the research all point to the conclusion that it is indeed possible to implement the product service extension successfully. Tests relating to the customer as well as the service provider perspective have proven themselves implementable due to low overall printing costs and fast print time enhancing the customer shopping experience. Together with an indication of product satisfaction as well as creating a strong customer-product connection through the co-design experience it contributes to a circular economy. Furthermore, the overall consistent printing costs, as well as the insignificant time differences in the experiments total time, support the implementation of a PSS in a retail setting.   Research Limitations - This research is confined to, and based on, the Monki and Re:textilebrief as well as a Business Model Canvas so therefore, no other ideas than the ones stated in the brief have been explored. The research´s inferences are limited to the given conditions as well as a laboratory setting. Further, the experimental research study will only test pocket shaped artwork on 100 percent cotton denim jeans using a Brother GTX 4 printer as a chosen direct to garment printer. The scope of the customer case study can be described as surveying as well as observing 40 of the visitors of the 2018 Fashion days and Exit at the Swedish School of Textiles while they test the proposed PSS in a mock-up retail store setting without an actual sales transaction.   Further Research - The next logical step would be to run the tests in a real-life retail store as opposed to the laboratory setting. After the proposed product service extension is implemented at scale POS data could be gathered in order to establish the customers’ true willingness to participate in the customisation experience in-store. Additionally, a longitudinal continuation of the study would give answers to some of the indications arising from the case study, such as whether the mass customisation could truly serve as a brand strengthening activity or lead to an extended garment lifecycle in reality.