Shape-Shifting Robot Forms From Magnetic Swarm

i think the movie is pretty much a source for this in itself, if you do a little logical thinking.
They have the idea, and they know how they want it.
they just don`t know of any way to make it small enough, and they don`t have the materials that is needed to make it work. It would need production in nano scale (wich is still being figured out), and a material that allows an easy change in the magnetic structure, so it kan bind itself to any other of the same material at any point around a spherical construction. A change in magnetfield can also give a change in colour (corect magnetic field can bend light so only certain colour specters reflect.)
So they know how to do it, just not HOW.