The DragonFlex, world’s first 3D-printed steerable Minimally Invasive Surgery (MIS) instrument, showing promising results for the medical field, is made by means of 3D-printing, and features simple assembly, while exhibiting high bending stiffness. In this research, the possibilities with additive manufacturing are explored even further, by minimizing the number of parts and thereby reducing the assembly time. The objective of the study was to design a one-part instrument, based on the DragonFlex, having the same functionality as the DragonFlex, while only requiring the assembly of the control wires. This one-part instrument is called the MonoFlex. In an iterative process of designing in SolidWorks (2018) and testing printed samples, the design of the MonoFlex was developed until final prototypes were obtained, both with and without steering segments. Final compression and torsion tests showed that the grasping forceps side and the control handle side, broke when exposed to torsion moments of 32.9 Nmm and 20.8 Nmm respectively and compression forces of 0.2 N and 1.5 N respectively. When the instruments were exposed to tensile forces up to 19.6 N, both sides did not show any sign of failure. The maximum grasping force reached was 2.4 N, lower that the average grasping forces (of 10 – 20 N), required to grasp tissue. The printed parts were slightly different from the parts drawn in SolidWorks, this was because of the incomplete addition of support material, and the post-processing method. The working principle of a one-part 3D-printed grasping prototype was proven. A recommendation for future research is to make the MonoFlex stronger and more durable by using multiple materials. This will bring medical technology another step closer to fully non-assembly 3D-printable MIS instruments.