The primary argument in favor of mass customization is the delivery of superior customer value. Using willingness-to-pay (WTP) measurements, Franke & Piller (2004) have recently shown that customers designing their own watches with design toolkits are willing to pay premiums of more than 100% (DWTP). In the course of three studies, we found that this type of value increment is not a singular occurrence but might rather be a general phenomenon, as we again found average DWTPs of more than 100% among customers designing their own cell phone covers, T-shirts, and scarves. Building on this, we discuss the sources of benefits that are likely to explain this tremendous value increment. We argue that compared to conventional standard products, a mass-customized product might render the following utilitarian and hedonic benefits: (1) First, the output might be beneficial as self-designed products offer a much closer fit between individual needs and product characteristics. In addition to this mere functional benefit, extra value might also stem from (2) the perceived uniqueness of the self-designed product. As the customer takes on the role of an active codesigner, there may also be two general 'do-it-yourself effects': (3) First, the process of designing per se is likely to allow the customer to meet hedonic or experiential needs (process benefit). (4) Customers may also be likely to value the output of self-design more highly if they take pride in having created something on their own (instead of traditionally buying something created by somebody else). This is referred to as the 'pride of authorship' effect.