Does anyone have a workflow or tool for producing multi color / multi material

Does anyone have a workflow or tool for producing multi color / multi material prints from models in openscad or blender?

Are other modelling tools better suited for this?

I am looking for tools that are capable of more than surface painting the model. The colours/materials should be more than skin deep, and include structural detail. e.g. a scratched surface should retain appearance, or a skeleton could be covered by flexible material.

From what I can see I would need to do at least the following.

A. Find regions that originate from single colors only
B. Find regions that originate from multiple colors
C. Develop a strategy(ies) for assigning colors to regions found in B.
D. Generate support material structures (could be before A.)

This could either be done directly from the 3D model,
or by sectioning the model and retaining hidden object boundaries.

Process C could assign overlapping regions using alternate algorithms such as vertically underlying, closeness to a unique color region, knitting filaments by alternating colors in the overlapped region to make ‘plywood’, etc

Has anyone done any work towards such a process?

Update 7 Jan 2019 :-
Looks like 3 main options are out there, - AMF, OBJ and 3MF.

Here are two good reads.

Slicer3 and Cura can take either AMF files or multiple STL files. On paper, slicer3 seems to be more capable of multimaterial at present, with cura limited to two extruders.

Meshmixer can work with AMF and OBJ files.

Toolchain options are documented in

As expected, the $$$ tools are all capable of working in this space.

To self-answer the original question,
Export to AMF, OBJ or multiple STLs
Load into Meshmixer
Slice in MeshMixer, slicer3 or Cura
or
Use Microsoft 3D Builder and 3MF
or
Spend $$$ on a professional tool

I now need to test the theory.

Here is a link to a very simple Openscad model that illustrates the basics of what I am wanting to do.