This study focuses on additive manufacturing (AM) to remodel an ergonomically optimized Leiqin leg rest. To address the design deficiencies of traditional leg rests regarding playing comfort and stability, iterative optimization techniques were employed alongside the Theory of Inventive Problem Solving (TRIZ). Photosensitive resin material was chosen, and a parametric modeling approach was utilized to accurately construct the leg rest model, resulting in the successful development of a double-layer rotating arc-shaped leg rest. Systematic acoustic testing and semi-structured interviews with ten Leiqin players were subsequently conducted for evaluation. The results indicated that the redesigned leg rest significantly outperformed traditional designs in terms of both comfort and stability. This study not only validates the application value of additive manufacturing in enhancing traditional musical instruments but also offers a new technological paradigm for the ergonomic design of musical instrument accessories.