Sashimono is a traditional Japanese woodworking technique known for its intricate, precise joinery assembled entirely without nails, screws, or adhesives. Developed during the Edo period (1603–1868), sashimono reflects a philosophy of sustainability, structural integrity, and aesthetic refinement. Its enduring appeal lies in its ability to produce long-lasting, flexible wooden structures that respond naturally to environmental changes, such as humidity and temperature fluctuations. The technique uses various types of joints, each one designed for specific structural or decorative purposes. These joints rely on geometric precision, friction, and symmetry to achieve both mechanical stability and visual harmony. This study focuses on analyzing the mechanical behavior of sashimono joints through finite element methods (FEM). Several joint typologies were modeled in 3D and fabricated using PLA via additive manufacturing. These physical models were subjected to both digital simulations and real-world stress testing to evaluate their load distribution, adaptability, and performance under tension. Special attention was given to how joint geometry—particularly contact surface area and symmetrical alignment—affects mechanical performance. By combining traditional craftsmanship with advanced modeling and 3D printing, the research aims to demonstrate how sashimono principles can inspire innovative, sustainable solutions in modern design and engineering. The findings support the relevance of sashimono in contemporary contexts such as modular construction, eco-conscious architecture, and furniture design, aligning with current trends in minimalism and resource efficiency. This interdisciplinary approach highlights the potential of ancient techniques to address present-day technological and environmental challenges.