We present a paradigm for natural and exploratory shape modeling by introducing novel 3D interactions for creating, modifying, and manipulating 3D shapes using arms and hands. Though current design tools provide complex modeling functionalities, they remain nonintuitive for novice users. Significant training is required to use these tools since they segregate 3D shapes into hierarchical 2D inputs, binding the user to stringent procedural steps and making modifications cumbersome. On the other hand, the use of computer-aided design (CAD) systems is typically involved during the final phases of design. This leaves a void in the early design phase wherein the creative exploration is critical. We present a shape creation paradigm as an exploration of creative imagination and externalization of shapes, particularly in the early phases of design. We integrate the capability of humans to express 3D shapes via hand-arm motions with traditional sweep surface representation to demonstrate rapid exploration of a rich variety of 3D shapes. We track the skeleton of users using the depth data provided by low-cost depth sensing camera (Kinect). Our modeling tool is configurable to provide a variety of implicit constraints for shape symmetry and resolution based on the position, orientation, and speed of the arms. An intuitive strategy for shape modifications is also proposed. Our main goal is to help the user to communicate the design intent to the computer with minimal effort. To this end, we conclusively demonstrate the creation of a wide variety of product concepts and show an average modeling time of a only few seconds while retaining the intuitiveness of the design process.