The two form a burgeoning bond, threatened at times by the robot's instincts to find someone like himself and, finally, by a much larger robot on a mission. (booklistonline.com)
Each builds components at the molecular level, feeding those components to increasingly larger robots until a full - size product is created. (newscientist.com)
I also remember an extremely large robot whose foot you had to enter. (waypoint.vice.com)