Someone once said: “If the shoe fits, buy it in every colour.” However, in a time where there is much more awareness for the problems of overconsumption and the throwaway culture, this is not a viable option anymore. But what if you only have to buy one pair of shoes (or any object) that changes colour to match your outfit or mood of the day? Researchers from MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) are working on a way to make that reality: presenting ColorMod, they developed 3D printable ink that changes colour when exposed to ultraviolet light, even after printing the object.

According to the team, previous colour-changing systems have been somewhat limited in their capabilities, using single colours and 2D designs. To move beyond single-colour systems, the MIT team developed a simple hardware/software workflow. First, using the ColorMod interface, users upload their 3D model, pick their desired colour patterns, and then print their fully coloured object.

After printing, changing the multi-coloured objects involves using ultraviolet light to activate desired colours and visible light to deactivate others. Specifically, the team uses an ultraviolet light to change the pixels on an object from transparent to coloured, and a regular office projector to turn them from coloured to transparent. The team can recolor a multi-coloured object in just over 20 minutes, and they claim that number will decrease significantly with future improvements.

The team’s ink is made of a base dye, a photoinitiator, and light-adaptable dyes. The light-adaptable (photochromic) dyes bring out the colour in the base dye, and the photoinitiator allows the base dye to harden during 3D printing.

While the project is currently focused on plastics and other common 3D printing materials, the researchers say that eventually people could instantly change the colour of their clothes and other items.

Photos: MIT CSAIL