Soft robotics, as a new dimension in robotics, is an rapidly growing research area. Fully compliant mechanisms and structures can be built using soft materials. Having a fully compliant system -a monolithic body- will reduce the manufacturing and assembly costs and show a whole-body bending performance similar to its natural counter-parts. Current prosthetics, particularly fingers and hands, require significant manufacturing and assembly operations. Using additive manufacturing (aka 3D printing), low cost and high performance prosthetic devices can be established. In this study, we report on a fully compliant finger which is 3D printed with a modified low-cost 3D printer based on the Fused Deposition Modelling (FDM) technique. Prior to the finger fabrication, the bending behavior of some well-known flexure hinges were modelled and experimentally evaluated to find the most suitable design for a fully compliant prosthetic finger. Experimental and numerical results from the finite element analysis for the hinges and the complaint finger are in good correlation, encouraging us to establish a single piece prosthetic hand in the near future.