The mobile devices have grown rapidly with the progresses of information technology those years. The mobile devices, such as i-Phone, i-Pad, Tablet PC and smart-phone, have become personal and business tools. Those devices are specially developed for mobile users on the basis of the conceptual design of personal digital assistant (PDA) long time ago, but the scopes of the usages extend much more extensive through integrated multimedia needs. This paper proposes a model called integrated usability model (IUM), derived from the technology acceptance model (TAM), to transfer the design criteria into the design guidelines. By using IUM, the developers for multimedia mobile device can use the conceptual indicators like mobile, integration and convenience to reduce the large-scale design factors and evaluate the capability and acceptance for the users. It turns out that the developers can speed up the design processes and avoid the repeated and time-consuming reworks. A mobile multimedia device development for the integrated graphic hand-sketch tablet is presented in this paper. This development uses IUM to reduce the design criteria and then transfer the result criteria into design guidelines. This paper demonstrates the practices of the multi-demand product design as the case validation of IUM.