3D printers. I never get tired of thinking about all the possible applications, like building a brand new coffee table,

or building a brand new 3D printer, or finally getting that Strickland action figure everyone's been asking for.

But all of these great products have one thing in common - rigidity.

That means they're going to keep that shape once I print them, unless I take a flamethrower to them, or maybe a hacksaw.

But the advent of something called 4D printing could turn all of that on its head!

That's right, it's one "D" better!

Actually, it's not just a catch phrase, 4D printing is really about using a 3D printer to print out

self-reconfiguring, programmable material. Now imagine this. You have a non-living object

that can change its shape and behavior over time. It's kind of like a robot

, but there are no microprocessors, no circuit boards, no motors - in fact to you it looks like a string of plastic.

But you toss it into a kiddie pool, and upon contact with water

you now have a secret message spelled out in plastic cursive!

Skylar Tibbits, the man who really came up with this idea of 4D printing, has gone even further. He's created programmable sheet material.

It's a sheet of plastic that, when submerged in water, can clench up into the shape of a cube.

And a cube is just the beginning! More complex designs will mean

millions of more shapes - like self-folding origami! In the near future, imagine a smart

grid of plumbing, with pipes that can actually expand and contract in response to water demand.

Or maybe even heal if there is a frozen segment that breaks open. Or imagine self assembling furniture.

Print out a flat board and just add water, next thing you know it curls up into a rocking chair.

Now, wrap your mind around how useful this would be in a really hostile environment

, like low Earth orbit, where building stuff comes at a high cost and a high risk.

Now the prototypes we have seen so far have been pretty simple, but the promises are amazing!

Think about it on the really big scale. What about skyscrapers and bridges.

If we could make them out of smart materials like smart beams and smart bricks,

they could heal themselves after weather damage or prepare for something massive like an earthquake.

Or we flip it. We go on to the very small scale and now we have micro particles moving around in our bodies

, maintaining our health. You might be wondering, how much complexity

can build up out of stuff that changes its shape without computers or electromechanical motors.

Lets think about proteins for a second. Proteins are pretty much what make any basic

animal function possible on a cellular level. And a protein is really self-reconfiguring material.

It's a polypeptide. It's a long chain of amino acids.

So once again we're playing Copy Cat to mother nature. Now lets not get ahead of ourselves,

I'm not actually suggesting that we're going to be printing out some sort of plastic replicant

that can gain self-awareness and yearn for more life. But maybe we will.

In fact, it's hard for us to predict right now. We're just seeing the very beginning of this technology,

and the complexity could become truly amazing. So, how would you use 4D printing?

Let us know! Leave a comment below, we promise we're going to read every single one of them and

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