This thesis investigates the feasibility and effectiveness of Haptic Aided Design (HAD) which can be used to facilitate the design process through multimodal interface. As a possible paradigm in virtual reality technologies, haptic feedback offers the designers an approach for enhancing the traditional input-based method used in Computer-Aided Design (CAD) system. Users can interact with 3D objects in the virtual environment and at the same time be able to have the tactile sensation during the design process. Moreover, such interface offers the designers a human-in-the-loop methodology where they are able interact with virtual prototypes modeled in the application environment. In the thesis, we developed two preliminary HAD environments to validate the integration of the haptic device with CAD system. In both of these environments, users are able to feel the force of simulated devices and intuitively modify design parameters through interaction with force feedback device. In order to evaluate the feasibility of proposed HAD interfaces, we conducted informal user studies where participants are asked to explore discretized design space of virtual prototypes. The experimental results suggest that these virtual prototypes integrated with haptic features can facilitate product development and may have great potential in future virtual reality design environment.