Since atoms have well understood light absorption properties, predictions can be made about the depth of a shadow cast, improving communication between the individual atoms performing calculations.

ENGADGET: Researchers capture a single atom's shadow, has implications for quantum computers

However, the researchers appeared confident that these setbacks could be overcome and added that future 3D printers should permit greater control over reflectivity, light absorption and other factors allowing toy designers to incorporate additional functionality.

BBC: Disney develops 3D-printed lighting for toys

Here, plastics that are black to the eye actually reflect a reasonable amount of light, so it is possible to get a meaningful absorption spectrum.

ECONOMIST: Recycling

The audience becomes entranced precisely by the means of making the spectacle, an absorption that, aided by menacing sound and flashing light, focusses attention on the devastation of war and, by contrast, the horsiness of a horse the rearing, twitching, and nuzzling through which its nobility and affection pour out.

NEWYORKER: Battle Stations