Flat feet is a widely recognized condition with a significant incidence in the population. However, currently prescribed foot orthoses are often uncomfortable for patients, as they tend to be excessively rigid or fail to provide adequate support over an extended period. In order to address this issue, the present research focused on the use of thermoplastic elastomer (TPE) material in the design of customized orthopedic insoles. This approach represents an innovation in manufacturing methods by incorporating advanced technologies, such as 3D printing, with the aim of providing not only greater comfort for patients but also adequate support for the foot, helping to promote correction or improvement of the symptoms of their condition. In this study, patients were monitored over a period of 3 months to assess the deformation of the insoles and to ensure that they provided the necessary support for treatment. The results were favorable, as the deformation of the insoles was minimal, and the primary support structure remained in good condition, fulfilling the proposed objectives in terms of functionality and durability.