This work details the redesign of the biomechanical finger for the HandBot-Kid prosthetic hand. This study aims to develop an adolescent-targeted prosthetic hand that improves upon current commercial offerings. To address these needs, the initial finger design was developed to integrate a four-bar mechanism. This mechanism was selected for its capacity to emulate flexion–extension movements with a degree of naturalness and similarity to those of a real finger. The redesign process and the implementation of additive manufacturing techniques have facilitated the optimization of the manufacturing process of the parts. The initial design used conventional manufacturing processes using Computer Numerical Control (CNC) machinery for the aluminum parts. For the redesign process, methodologies such as: Design for Additive Manufacturing (DFAM) and Design for Assembly (DFA) have been implemented. The primary objective of these methodologies is the optimization of the manufacturing process of the parts in terms of cost and time. The DFAM methodology has been implemented in this work to improve the manufacturing process of the parts, aiming to reduce printing times. The incorporation of the DFA concept ensures that downstream assembly processes are integrated into the finger redesign process, aiming to simplify the assembly of the components. The incorporation of DFAM and DFA methodologies into the additive manufacturing processes leads to an optimization of the finger manufacturing process. This optimization is reflected in the reduction of the manufacturing and assembly times of the parts.