A New Way to 3D Print in Two Colors

Printing in two different colors on an FFF (fused-filament fabrication) 3D printer usually requires either dual extruders or a filament-swapping system like the Mosaic Palette device. But both of those options have their downsides, including cost and complexity. The current Mosaic Palette 3, for example, costs $699. And adding a second extruder to a printer that isn't designed for it is a substantial job. That's why Heinz came up with an innovative dichromatic rotating nozzle extrusion system for 3D printers that allows for printing in two colors.

Heinz's inspiration for this project was the humble toothpaste tube. A common gimmick for decades now is for toothpaste to come out of the tube with colored stripes of "minty flavor" or "gingivitis-fighting formula." Those toothpaste tubes aren't anything special, the "extruded" toothpaste simply retains the color pattern already inside of the tube. Heinz figured out that they could reproduce that effect on a 3D printer by feeding two different filament colors into the same hot end.

The extruded plastic is dual-color. One half of the extruded filament is the first filament and the other half is the second filament — they do not mix. That effect by itself wouldn't be useful, because the position of the each color would always be the same. The result would be a part that is the first color on one side, the second color on the opposite side, and the middle would be a muddy mix depending on the toolpaths created by the slicing software.

To compensate for that, Heinz created a special build plate that rotates on an axis parallel to the hot end nozzle. That allows the printer to select which of the two colors faces outward on any given extrusion line. Heinz uses the Nozzleboss Blender add-on to modify g-code files, so that the build platform rotation coordinates with the normal Cartesian printer movement. Using a Blender texture map as a reference, Nozzleboss determines which color is visible on any given surface. The result is dual-color 3D printing.