In this study, we consider the development of a device for handling small parts for automatic product assembly in factories. Many robotic hands and one-degree-of-freedom grippers have been proposed as grasping parts; here, we focus on the shape of the tips of a handling device for picking up small parts robustly and agilely. In this research, we propose a concept for a handling device for picking up small round parts. In this concept, the handling device cages an object without letting the object escape from its tips before closing them completely and then grasps the object robustly at a unique position of the tips. Using this caging and self-alignment concept, the handling device can pick up objects robustly and agilely. In this paper, we focus on a method for designing the shape of the device's tips using the concept of caging and self-alignment of objects. We also develop the robust and agile pickup device (RAPiD) with tips designed by the new method and present experimental results that illustrate the validity of the concept and the ability of RAPiD to handle small parts.