Using a 6-DOF robotic manipulator for material extrusion additive manufacturing (AM) enables conformal printing onto complex surfaces while orienting material fibers at desired directions. Compared to a traditional 3D printer, conformal printing can produce parts with good surface finish, less number of layers and enhanced mechanical properties. In this paper, we present a three-nozzle extrusion system which can be attached to a robot. This system allows the robot to achieve conformal 3D printing with multi-resolution. One extruder is for printing support materials and the other two extruders are for fabricating structural material with different resolutions. The interior regions of the part are fabricated with a bigger diameter nozzle and the surface of the part is printed with a smaller diameter nozzle. This multi-resolution printing not only speeds up the build times but also produces the good surface finish. In previous work, we demonstrated multi-resolution 3D printing using two robots. The contributions of this paper are design and fabrication of a three-nozzle extrusion system, calibration process for the system, and its validation. The validation of the calibration was done by printing linear and circular patterns using different nozzles, and evaluating relative dimensional accuracy. This work will enable a single robot to perform multi-resolution conformal 3D printing.