Cellular shape shifting tangible systems
Please note: These are possible products of advanced productive nanosystems (nanofactories) and not productive nanosystems that make things from raw atoms themselves. Far term goal productive nanosystems do not consist out of swarming nanobots. The old molecular assembler concept was an early simple bio-analogy. It is obsolete for a long time by now.
There are some ongoing experiments with current day technology in which we gain some preliminary experience.
- Wikipedia Self-reconfiguring modular robot (contains a good overview over current experimental macroscopic systems)