In this article, the authors propose that the canonical customer-toolkit dyad in mass customization (MC) should be complemented with user communities. Many companies in various industries have begun to offer their customers the opportunity to design their own products online. The companies provide web-based MC toolkits which allow customers who prefer individualized products to tailor items such as sneakers, PCs, cars, kitchens, cereals, or skis to their specific preferences. Most existing MC toolkits are based on the underlying concept of an isolated, dyadic interaction process between the individual customer and the MC toolkit. Information from external sources is not provided. As a result, most academic research on MC toolkits has focused on this dyadic perspective. The main premise of this article is that novice MC toolkit users in particular might largely benefit from information given by other customers. The pioneering research conducted by Jeppesen (2005), Jeppesen and Frederiksen (2006), and Jeppesen and Molin (2003) has shown that customers in the computer gaming and digital music instruments industries are willing to support each other for the sake of efficient toolkit use (e.g., how certain toolkit functions work). Expanding on their work, this article provides evidence that peer assistance appears also extremely useful in the two other major phases of the customer's individual self-design process, namely the development of an initial idea and the evaluation of a preliminary design solution. Two controlled experiments were conducted in which 191 subjects used an MC toolkit in order to design their own individual skis.