In use since at least the 4th century AD, dichroic glass displays different colors depending on how it's being viewed. Now, Dutch scientists have produced the effect in a material that can be used to create 3D-printed objects – and it's not just a novelty, as it could have practical applications.

A team of researchers at Wageningen University started with regular polyvinyl alcohol (PVA), which is a widely-available polymer commonly used as a 3D printing medium. To this they added gold nanoparticles of varying sizes – not much of the gold was needed, as it ended up constituting only 0.07 percent of the resulting composite material's weight.

The team then proceeded to 3D-print a variety of objects, using the gold-infused PVA.

When those items are viewed with the light source on the same side of the object as the observer, the nanoparticles reflect the light, causing the whole item to appear opaque brown. If the light source is on the other side of the object, though, the light passes through the particles, causing the object to appear translucent violet.

Once commercialized, the material could be used by anyone, in off-the-shelf 3D printers. And while it certainly could be utilized to produce artwork or jewellery, it might also be used to print items such as optical lenses that allow some colors of light to pass through, while reflecting others.

The scientists are now refining the technology, looking at the effects that can be produced using different types of nanoparticles and printing materials.

A paper on the research was recently published in the Beilstein Journal of Nanotechnology. You can see some of the 3D-printed objects in color-changing action, in the video below.