This study analyzes which factors prompt customers to attribute value to products they design themselves using mass-customization (MC) toolkits. The assumption that self-design delivers superior customer value is fundamental to the concept of MC toolkits and can be found in almost any conceptual work in this field. However, spectacular failures reinforce the practical relevance of developing a deeper understanding of why and when MC toolkits generate value for customers-and when they do not. Research to date has assumed that the closer fit between the self-designed product's characteristics and the preferences of the customer is the dominant source of value. In this research, it is asked whether the enjoyment and perceived effort of the self-design process have an additional impact on the perceived value of self-designed products. This question is interesting because one could argue that a rational actor would hardly be willing to pay ex post for an economic good already consumed. The hypotheses are tested on 186 participants designing their own scarves with an MC toolkit. After completing the process, they submitted binding bids for "their" products in Vickrey auctions. Therefore, real buying behavior, not merely stated intentions, is observed.