Software company Autodesk, who so far has released their Ember SLA 3D printer, has filed a patent for what seems to be a multi material 3D printer based on FDM technology.
According to the patent, the system includes an extruder with two or more material entry ports and a mixing chamber. A controller can dynamically change the mix ratio of materials fed into the chamber, before being deposited. This system could allow for creating objects with different properties and colours.
A similar approach has been made by UK-based start up BotObjects, which has been acquired by 3D Systems followed by the launch of the Cube Pro C multi-colour 3D printer.