Patients with hand or little finger amputation suffer from manual skill loss and both aesthetic and psychological aspects. In this research we aim to enhance the grasping abilities by adding an additional thumb, involving multiple iterations of the palm's design. Congenital anomalies, such as polydactyly show people that hold extra fingers have advantage in manual dexterity. There are studies where a sixth finger added to the hand (a thumb) improves manual skills. Salvietti [35] , propose a

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... tion to compensate the grip abilities in patients with stroke, adding a sixth adjustable robotic finger. Among its results the extra finger acts as a motivational assistance device. Segura [36] indicate that extra artificial limbs, offer the possibility of increasing the workspace, dexterity, resistance and reduce user fatigue. Starting from existing robotic hands models like Inmoov and Parloma, are analyzed convergence patterns of design, morphology of the palms of the hands, the degree of freedom for two thumbs, manufacturing costs, assembly, and 3D printing patterns to generate remixes. In this work a mechatronic design methodology is used. Through the convergence patterns and the use of 3D printing, Inmoov and Parloma remixes were assembled, both compared, and we got four additional remixes. The approximate cost of manufacturing is above US$530.00 and required more than 120 hours of printing. In later studies, each link and join hand will be acted with intelligent material and force sensors attached to each fingertip to compare grasping and dexterity behaviors of a normal hand to an enhanced one. Abstract Patients with hand or little finger amputation suffer from manual skill loss and both aesthetic and psychological aspects. In this research we aim to enhance the grasping abilities by adding an additional thumb, involving multiple iterations of the palm's design. Congenital anomalies, such as polydactyly show people that hold extra fingers have advantage in manual dexterity. There are studies where a sixth finger added to the hand (a thumb) improves manual skills. Salvietti [35] , propose a solution to compensate the grip abilities in patients with stroke, adding a sixth adjustable robotic finger. Among its results the extra finger acts as a motivational assistance device. Segura [36] indicate that extra artificial limbs, offer the possibility of increasing the workspace, dexterity, resistance and reduce user fatigue. Starting from existing robotic hands models like Inmoov and Parloma, are analyzed convergence patterns of design, morphology of the palms of the hands, the degree of freedom for two thumbs, manufacturing costs, assembly, and 3D printing patterns to generate remixes. In this work a mechatronic design methodology is used. Through the convergence patterns and the use of 3D printing, Inmoov and Parloma remixes were assembled, both compared, and we got four additional remixes. The approximate cost of manufacturing is above US$530.00 and required more than 120 hours of printing. In later studies, each link and join hand will be acted with intelligent material and force sensors attached to each fingertip to compare grasping and dexterity behaviors of a normal hand to an enhanced one. Reviewer 1: Figure 7 : Please indicate clearly the different hands so that it is obvious to the reader. Here we made a explanation about it Fig. 7. Spherical grasp: a) Inmoov hand, b) Kool Hand. Power Grasp: c) Inmoov hand, d) Kool hand The application of the remix-based technique in the palm, allowed to restructure the design offered by Parloma hand, from the metacarpal joint structure to the trapezium in the thumbs, and through recombination with Inmoov Hand, facilitated improvements in the reduction of the palm area by 8%, reduction of assembly components, 22% weight reduction, 4 hours of less printing time, 19% cost reduction, as well as the increase of experience in the parameters management with AM. Kool Hand was evaluated qualitatively for its appearance, and normal and unconventional prototypes were compared, which resulted in a surprise effect of 94% in the surveyed population. The fact that most of the research is oriented to prosthetics and robotic hands, similar to the human hand, makes Kool Hand a different innovative prototype, which modifies the grip ecosystem with respect to traditional robotic hands. In another work, recombination will be performed by compilation between the remix 4 and Kool Hand, as well as the evaluation of mechanical tests, cosimulation, and extend the grip tests to other products. This research contributes to the knowledge of the remix technique, since there is currently limited development in this respect, and it is important to mention that at the time of writing this work, a similar prototype was not identified in online digital and open access communities.