The fashion industry faces urgent challenges related to overconsumption, material waste, and consumer detachment from garment lifecycles. While circular economy (CE) principles offer a promising alternative, strategies that actively engage consumers in circular practices remain underexplored. This study presents the Circular Shirt Builder (CSB), a physical apparel configurator designed to promote circular behaviours through modular garment design and embodied customisation. Using a Living Lab methodology, 19 participants engaged with the CSB in a stakeholder engagement platform in a retail-like setting, assembling modular shirts from a predefined library of components. The study employed a dual analysis approach: inductive thematic analysis and a deductive evaluation using the wellbeing framework for consumer experiences in the circular economy of the textile industry. Findings suggest that the CSB can foster emotional attachment, support learning about garment construction, encourage creative self-expression, and prompt reflection on consumption habits. Several wellbeing dimensions, such as playfulness, agency, and prospective thinking, appeared to be activated through the hands-on interaction. This research indicated that configurator tools grounded in circular and wellbeing principles may support long-term product use, more mindful consumption, and greater consumer involvement in transitions toward a circular textile economy.