parallel_prankster writes "Researchers at MIT are developing
tiny robots that can assemble themselves into products and then
disassemble when no longer needed. 'A heap of smart sand would
be analogous to the rough block of stone that a sculptor begins
with. The individual grains would pass messages back and forth
and selectively attach to each other to form a three-dimensional
object; the grains not necessary to build that object would
simply fall away. When the object had served its purpose, it
would be returned to the heap. Its constituent grains would
detach from each other, becoming free to participate in the
formation of a new shape.' To attach to each other, to
communicate and to share power, the cubes use 'electropermanent
magnets,' materials whose magnetism can be switched on and off
with jolts of electricity."