In this paper, we present DupRobo, an interactive robotic platform for tangible block-based design and construction. DupRobo supported user-customizable exemplar, repetition control, and tangible autocompletion, through the computer-vision and the robotic techniques. With DupRobo, we aim to reduce users’ workload in repetitive block-based construction, yet preserve the direct manipulatability and the intuitiveness in tangible model design, such as product design and architecture design. Through a user study with 12 participants, we found that DupRobo significantly reduced participants’ perceived physical demand, overall efforts, and frustration in the process of block-based structure design and construction, compared to the situation without DupRobo. In addition, the participants rated DupRobo as easy to learn and use.