The Erector brand is now owned by Nikko, a Japanese maker of remote-control toy airplanes and cars.

FORBES: Global Life

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

Engineers could control which bits of the eyes were illuminated in a specific colour, to make the toy appear as if it was rolling its eyeballs, blinking, or showing two small throbbing hearts.

BBC: Disney develops 3D-printed lighting for toys