Purpose -This paper aims to establish a multiscale topology optimization method for the optimal design of non-periodic, self-supporting cellular structures subjected to thermo-mechanical loads. The result is a hierarchically complex design that is thermally efficient, mechanically stable, and suitable for additive manufacturing. Design/methodology/approach -The proposed method seeks to maximize thermo-mechanical performance at the macroscale in a conceptual design while obtaining maximum shear

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... odulus for each unit cell at the mesoscale. Then the macroscale performance is re-estimated and the mesoscale design is updated until the macroscale performance is satisfied. Findings -A two dimensional MBB beam withstanding thermo-mechanical load is presented to illustrate the proposed design method. Furthermore, the method is implemented to optimize a threedimensional injection mold, which is successfully prototyped using 420 stainless steel infiltrated with bronze. Originality/value -By developing a computationally efficient and manufacturing friendly inverse homogenization approach, the novel multiscale design could generate porous molds which can save up to 30% material compared to their solid counterpart without decreasing thermo-mechanical performance. Practical implications -This study is a useful tool for the designer in molding industries to reduce the cost of the injection mold and take full advantage of additive manufacturing.