A three-dimensional (3D) printing technology that facilitates continuous printing along a combination of Cartesian and curvilinear coordinates, designed for in vivo and in situ bioprinting, is introduced. The combined Cartesian/curvilinear printing head motion is accomplished by attaching a biomimetic, flexible, “tendon cable” soft robot arm to a conventional Cartesian three axis 3D printing carousel. This allows printing along a combination of Cartesian and curvilinear coordinates using five independent stepper motors controlled by an Arduino Uno with each motor requiring a microstep driver powered via a 12 V power supply. Three of the independent motors control the printing head motion along conventional Cartesian coordinates while two of the independent motors control the length of each pair of the four “tendon cables” which in turn controls the radius of curvature and the angle displacement of the soft printer head along two orthogonal planes. This combination imparts motion along six independent degrees-of-freedom in Cartesian and curvilinear coordinates. The design of the system is described together with experimental results, which demonstrate that this design can print continuously along curved and inclined surfaces while avoiding the “staircase” effect, which is typical of conventional three axis 3D printing along curvilinear surfaces.