Collada Mesh Export with Multiple Textures

[micheus]

How do I get each face (it's shape) 'external' to W3D so that I can create the image map specific to the face, then import and 'snap image' to the material?

You have to create the UV map and at this point, when you use Create Texture in the AutoUV an image will be available in the Outline window where you can use the context menu - Make External to export the faces outline. After you paint your texture, back to W3D you just need to use the context menu and Refresh the image.

Also I presume I can have multiple faces associated to a single material, and therefore have a image map applied to a 'group' of faces, correct?

as dgud told you, textures are material property, so you need to assign a material for that group of faces and then UVmap it.