Over the years, toolkits have been designed to facilitate the rapid prototyping of novel designs for graphical user interfaces, physical computing, fabrication, tangible interfaces and ubiquitous computing. However, although evaluation methods for HCI are widely available, particular techniques and approaches to evaluate technical toolkit research are less well developed. Moreover, it is unclear what kind of contribution and impact technical toolkits can bring to the larger HCI community. In this workshop we aim to bring together leading researchers in the field to discuss challenges and opportunities to develop new methods and approaches to design, evaluate, disseminate and share toolkits. Furthermore, we will discuss the technical, methodological and enabling role of toolkits for HCI research.