DNA origami enables the bottom-up fabrication of 3D nanostructures with high precision and wide design flexibility by utilizing multiple short DNA strands (staples) that only bind at predefined positions. This design method, however, requires unique staple sets for each structure, which leads to significant cost burden when a designer wants to create multiple structures having different geometries or mechanical stiffness. Here we provide a rational modular design method that can control the mechanical stiffness of the modules individually, and bent them by applying geometrical confinement mediated by a dsDNA adjuster component. Solution shape prediction based on finite element analysis applied throughout the design process and the results were validated experimentally.