Smart Sand shares information, joins together to form objects. From CNET: “Researchers at MIT have developed a robotic system for duplicating shapes, a potential alternative approach to three-dimensional printing. The Distributed Robotics Lab at MIT today detailed research aimed at replicating objects by essentially carving them from an unformed pile of ‘smart sand’ or ‘robot pebbles.’ The vision is to have these miniature robots automatically create replicas of different sizes with only an original shape to work with.”

Only a computer demo at this point: