When we think of 3D printing, we often consider the product produced, not the waste.

Professor Stefanie Mueller and fellow researchers from MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) are exploring a more efficient way to cut down on print jobs: objects that change color.

With the Massachusetts Institute of Technology’s “ColorMod” interface, users have the ability to select a color pattern – and then try another.

Mueller led the development of the ColorMod research prototype, which relies upon a unique manufacturing component: a 3D-printable ink that responds to ultraviolet light.

How ColorMod Works

ColorMod’s software and hardware allow a designer to first upload a 3D model into the interface. After selecting color patterns, the user prints the object – say, a piece of jewelry.

The object, however, is made from a unique, customized ink made of a base dye, a light-adaptable dye, and a photoinitiator. The 3D printable changes color when exposed to both UV and visible light.

The light-adaptable, or photochromic, dye draws out the base dye’s color, and the photoinitiator hardens the base dye during the 3D-printing process. The result: The 3D-printable dyes show color when exposed to UV light — and are made transparent again when exposed to visible light.

Once a design is placed in the projector, the ultraviolet light then activates and deactivates the designer’s specified pixels, according to the specified pattern, changing pixels from transparent to colored. A standard office projector reverses the process, transforming pixels from colored to transparent.

The recoloring process takes approximately 20 minutes, according to the researchers, who note that the task could be sped up with a more powerful light or more light-adaptable dye.

See the demo below.

Reducing Waste

The color-changing research, co-authored with Mueller along with postdoc Parinya Punpongsanon, undergraduate Xin Wen, and researcher David Kim, has been accepted to the ACM CHI Conference on Human Factors in Computing Systems, which takes place in April in Montreal.

Mueller has previously worked on several projects focused on reducing waste and streamlining the additive manufacturing process, including personalized 3D printing for consumers and a method for rapidly printing wire prototypes. Although the color-changing 3D printables are not set for commercialization, the MIT professor sees the prototype system as an efficient and cost-effective manufacturing method.

“With the amount of buying, consuming, and wasting that exists, we wanted to figure out a way to update materials in a more efficient way, which was largely the motivation behind this project,” Mueller told Tech Briefs.

According to the specified designs in the bottom of the image, ultraviolet light activates some colors, while visible light from a standard projector deactivate others. (Image Credit: MIT)

While the project currently works with plastic materials, the researchers say the system could someday be used to quickly change the color of apparel or other items.

Imagine if a shopper wants to try on an article of clothing or an accessory in real time. Retail stores, according to Mueller, could someday use a similar color-changing idea to customize products efficiently, and in real time.

Beyond consumers, the system also potentially serves design engineers looking to show and tell.

“Advertisers, product designers, and other professionals often present physical artifacts in client meetings, and it would probably be exciting for them to be able to show their client right in the meeting what their design would look like in a different color," Mueller said.

The MIT team is currently working on ways to improve the sometimes-grainy appearance caused by activating adjacent pixels that blur the resulting color – making, for example, red and blue pixels appear as purple. Mueller also hopes for the technology, and its development, to pick up the pace.

“As a next step we hope to speed up the printing process by using a more powerful light and potentially adding more light-adaptable dye to the ink,” said Mueller. “We also hope to improve the granularity of the colors so that more nuanced patterns can be printed.”

What do you think? How would you use color-changing 3D printables? Share your comments below.