The computer is no longer the center of attention. Thus, what we design is no longer the interface to the computer. Rather, what we design is a thing or an environment in which a computer might be used to create certain desired effects. Indeed, interaction design in a sense becomes the practice of giving form to artifacts or environments rather like any of the other design disciplines that we have know for centuries. However, giving form to computational things is highly complex and somewhat different than most other form-giving practices due to its temporal form element—its ability to change between states. Thus, an interaction design practice needs to encompass this temporal form giving in combination with physical form giving and performances of the interaction gestalt. In this paper, I propose this trinity of forms as a framework to unfold the practice of interaction design. I further demonstrate how computational composites present a way to work with the temporal form and the physical form in a process not too different from any traditional form-giving practice. Lastly, I point to some tools and techniques to deal with the interdependencies of the three form elements and thereby also demonstrate that a form- giving practice of interaction design is already well under way.