With the wide adoption of information technology, a customer can now actively participate in the design and production process for a wide range of products, as a 'prosumer'. A significant portion of the value for those products is generated through the prosumption process. However, a major challenge in prosumption is the efforts involved and the ideas required in the process. In this study, we ask whether social learning, the act of showing the focal consumer creations made by other consumers, can improve customers' project creation and purchase decisions. Arguable, by showing others' product design to the focal customer, the firm may help the customer learn ideas from peers, reduce her cost and uncertainty in evaluating the product and improve their self-efficacy. We conduct a large scale randomized field experiment in close collaboration with an Ecommerce platform specialized in customized photo products, and examine whether and how other users' photo collage design would affect the product design and purchase behavior of the focal user. Our experiment shows that under certain conditions, showing other users' design can be highly effective in influencing the purchase and design behavior of the focal customer, but firms must choose the right customers and carefully select the type of user design at play. Our study is among the first to test and understand whether and how firms can leverage social learning to improve customer prosumption.