An Autodesk patent has just been published which reveals possible plans for the software giant to enter the FDM/FFF 3D printing space. The patent, which details several innovative methods of printing with multiple materials and multiple colors, was filed on Sept 30, 2014 and just published this last week. It details multiple methods of mixing filament colors and also changing nozzle sizes during a 3D print. One method allows for the mixing of up to 7 different strands of filament within a single hotend. Additional details on the methods that they outline in this rather interesting patent filing can be found here:
http://3dprint.com/74984/autodesk-patent-multi-color


Below is a diagram of one of these 3D printing methods they outline: