Desktop 3D printing has given birth to a rapidly growing industry, but until recently 3D printed items have been limited to monochrome. At Ultimaker, we strive to push the boundaries of desktop 3D printing applications: in collaboration with the Delft University of Technology, one of our engineers has developed a technique to achieve grayscale printing using an Ultimaker 3 . Using this method enables a user to print an object with varying tones using two colors.

Tim Kuipers has made use of a technique called linear halftoning to produce 3D objects with the appearance of full grayscale imagery. The principle of halftoning is not a new concept—in fact, it dates back as far as the 17th century. The effect is demonstrated below:

In his co-authored research paper, Kuipers explains that linear halftoning “creates the perception of continuous tones by printing small patterns of discrete colors."

Following the principle of hatching, linear halftoning is used to create both black and white lines with varying thickness, which gives the viewer the appearance of grayscale imagery, while, in fact, the object consists of simple black and white lines.

Leveraging the dual extrusion capabilities of the Ultimaker 3, Kuipers was able to create the black and white lines that resulted in grayscale objects.

He further explains: "Full layers are printed with either white or with black filament, and at every layer, the printer alternates between printing with black and with white filament. The apparent grayscale tone is achieved by exposing more or less of the black filament compared to the white filament at a given location. Making black more exposed makes the 3D print appear darker at that location, while white makes it lighter."

Applications

This grayscale printing technique has applications in several areas. In prototyping, linear halftoning can be used as a design feature in developing conceptual models, as it is not limited to printing using a discrete set of colors. Alternatively, for manufacturing, it can be used to communicate technical details on the printed object. For instance, it can be used to identify how fragile different areas of a fabricated tool are by showing various intensities of blackness.