Prototyping is widely recognized as an effective method for quickly generating cost-effective designs and efficiently gaining user feedback early in the product life cycle. Over the past decade, the method has also been adapted and extensively used for mobile interfaces and devices. Because the design of handheld devices (e.g., PDAs and cell phones) involves complex software functionality as well as a need to be integrated with the customized controls and interaction of the physical device, it requires hardware and software prototyping that is challenging. Pering argues that one of the greatest issues of prototyping is to be efficient with the full range of tools, such as paper or high-fidelity prototypes. For interaction designers to overcome a range of prototyping challenges, they first must recognize that each new and greater level of functionality in prototype development means more implementation time. This article introduces a hybrid method of prototyping that utilizes paper and mobile device technology that is both quick to create and agile to use in the early stages of design without the need to implement a fully operational high fidelity prototype.