Enabling thin regions in aircraft wings with active control surface functionality is challenging in terms of the integration of high-power actuation systems in regions with small available volumes. This paper details the design of a winglet trailing edge surface composed of miniature fluid-actuated morphing unit structures (FAMoUS) that can potentially enable control surface deflections under the corresponding aerodynamic hinge moments. These FAMoUS actuators consist of a hybrid elastomer and metallic extensible hollow units into which incompressible fluids can be pumped thereby creating displacement and force and thus output work. Position control can be achieved in combination with the appropriate pump systems and shape-feedback sensors. This paper outlines the design, finite element analyses and manufacturing process of a demonstrator currently being fabricated for subsequent testing. These finite element analyses consist of detailed tuned material parameters obtained from testing on the individual unit structure tests as well as the inclusion of hydrostatic fluid elements to determine effective stiffnesses from the pressure-volume relationship between the housing structure and internal fluid. Manufacturing of the demonstrator is to be conducted using composite fabrication and machining techniques to ensure that the demanding tolerances and surface qualities are to be maintained. Outcomes of the manufacturing process and initial testing results show bimorph behavior under fluid pressure.