A 3D printing machine for fabricating high performance 3D integrated composite structures, where the machine includes a robot having a base portion, a robot arm and a rotatable connector secured to the arm opposite to the base portion, at least one source of an extrudable material, and an end-effector mounted to the rotatable connector and including at least one extruder module for extruding the extrudable material. The extruder module includes a nozzle assembly for extruding heated material out of the end-effector, and the end-effector is rotatable relative to the structure by the rotatable connector so that the nozzle assembly can be oriented normal to the part in different orientations without significantly changing a pose of the robot.