Additive manufacturing — or 3D printing — is 30 years old this year. Today, it’s found not just in industry but in households, as the price of 3D printers has fallen below US$1,000. Knowing you can print almost anything, not just marks on paper, opens up unlimited opportunities for us to manufacture toys, household appliances and tools in our living rooms.

But there’s more that can be done with 3D printed materials to make them more flexible and more useful: structures that can transform in a pre-programmed way in response to a stimulus. Recently given the popular science name of “4D printing,” perhaps a better way to think about it is that the object transforms over time.

Image: Shapeshifting: 3D printed materials that change shape over time (credit: Dan Raviv/Scientific Reports)