A system and corresponding method to move a rod of build material in a three-dimensional (3D) printing system uses a pusher. The rod of build material has distal and proximal ends relative to an extrusion head. The distal and proximal ends having distal and proximal end surfaces, respectively. The pusher engages with the rod and applies an axial force to at least a portion of the distal end surface of the rod for at least a portion of a path the rod travels toward the extrusion head. The axial force actuates the rod of build material without alteration, such as by shaving, fracturing, or otherwise deforming the rod of build material.