The cubes under the magnifying glass are wrapped in magnetic wires. The magnetism can be switched on and off, allowing the cubes to communicate and share power.

3-D Printing Is So Last Year: MIT's "Self-Assembling Sand" Builds Objects Instantly

It sounds like sci-fi, and it could eventually make rapid-prototyping seem quaint.

If Terminator 2 taught us anything, it was that a properly timed thumbs-up can make us cry. Also, autonomous, self-shaping blobs are a must-have on our checklist for the future.

Now, MIT professor Daniela Rus and student Kyle Gilpin are publishing a paper on building such a wonder goop. They tend to refer to the technology as a smart "sand," and they imagine scenario in which you could drop a small model into a vat of the sand, and the sand could sense that model’s contours and create a 3-D version of the object from that information. So you could drop in a tiny cup, the sand would sense the cup’s negative space and then it would shape into a cup that was 10x (or much more) larger.

Right now, the team is focused on developing an algorithm to make their approach possible—a hyper-efficient language that’s simple enough for each grain of sand to understand without massive processing power. It’s only with this language that the idea could hope to scale.

"The beauty of encasing a prototype of the object to be formed with the smart material is that we drastically reduce the communication burden on the system so that we are prepared to scale-up the number of modules in the system," Gilpin tells Co.Design. "If we used CAD or similar, we’d be forced to transmit a complete description of the shape to be formed to all of the modules. With 100 modules that’s okay, but somewhere on the way to a million, it becomes unreasonable. We don’t want to send a million messages, one for each module in the system, telling each whether it is a part of the shape we’re attempting to form or not."

To test their math, the teams has developed a prototype of the sand. (Gilpin calls these larger pieces "pebbles.") Each pebble is 10mm across and contains an independent processor along with magnets that enable the magical sticking trick. As cool as they may be, the resolution of this rapid manufacturing technology is really only as sharp as the building blocks are small. Think of them as 3-D pixels.

"Shrinking the hardware presents the biggest long-term challenge," admits Gilpin. "As we shrink the modules, we’ll have to look for alternative connection mechanisms. One possibility is using electrostatic forces instead of magnetic ones. This would allow us to replace the relatively bulky electro-permanent magnets with much smaller electrodes."

The researchers hold their prototype "smart pebbles."

That said, the technology’s promise is massive. You could build structures that were far smarter than even our most advanced 3-D printed parts (even those that we’re using within the human body), that can respond and adapt to their environment. "In addition to duplication, I would see our modules used for sensing tasks in constrained spaces," writes Gilpin. "Perhaps you could pour our modules down a pipe in order to both map the shape of the pipe while finding defects or cracks. The modules could potentially help reinforce those weak points…Because it can self-disassemble, perhaps it could be used as an intelligent scaffolding for bone, or even organ, regrowth. The system could sense and relay important information to doctors and then disassemble as the bone healed."

Gilpin knows that the technology is a ways off, believing it to be closer to a 10-year vision than a five-year one. In other words, this self-assembling sand could be waiting for us right where 3-D printing leaves off.

[Images by M. Scott Brauer/MIT]

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  • Jeff Kunkler

    At the current scale, what is the cost of making the modules? I am wondering how useful these could be to help fix our crumbling infrastructure (especially bridges). Could they lock together strong enough to make self-assembling forms for concrete?  Cpuld they self-weld together and become part of the material matrix in construction? (kind of a waste of a lot of copper and iron from the electromagnets in the current design, but maybe if done with lesser impact materials?  decidedly more low-tech but perhaps more useful in the short run? I would love to have this even as an educational toy!


  • brindys

    Great work!

    This reminds me the Terminator T1000 rising out of the checkered floor in the film Terminator 2.

  • vulgrin

    Just cut to the chase. How long until I can craft "golem" copies of myself, as in David Brin's "Kiln People"?

  • Rob

    Ummmm, this is the first real step towards Teraforming.Or at least that's what T.V and Film has taught me, a self replicating dust or bacteria that sweeps across desolate expanses changing it into what ever you want or need. Hello 2050 holiday to Mars. 

  • Nicole Barker

    Amazing, fabricating with such a small building block would create almost flawless objects. I currently use the Thing-O-Matic for my 3D printing, but this is an entirely different level, with no seams or stitching.

  • Nnewton

    Here's the seed for a future virus of self-replicating 3-d objects. Without controls in place one could imagine free volumes being filled with unwanted replicas of unwanted originals.

  • Herb Meehan

    As I initially thought... there's nothing to see here.  More potential, promise, and sci-fi. 

  • M Harris

    Although the title does "oversell" the reality, discussion of concept (and in this case, viable prototype) is absolutely the opposite of "nothing to see here".  Sharing research, at whatever level of detail, is incredibly valuable, and in many cases, entertaining.  It's impossible to know what advances, applications or new concepts might otherwise have gone unexplored if it wasn't for the free flow of ideas.

  • Jesse B.

    This opens so many possibilities. If a viable version could be created the applications would only be limited by the imaginations of the users

  • zoey brown

    I agree. My mind was wandering just as I was reading. Think of what it could do in space!