Geneal Question About Creating an Add On I am a .NET Engineer. I don't know Python though. I am trying to find out of this scenario is plausible. Could an add-on be created that could take an ID map that was created in Blender Render and multiple imported diffused textures (maybe as many as 20) and then could "bind" a color (from the ID map) to each one of the imported textures and create a single diffuse map from the 20 textures. I am wondering if the Blender API surface area exposes the functionality to handle these tasks. I understand that this maybe too vague, but if you have experience writing add-ons and you think it is possible I could write up the required stories with acceptance criteria for a more specific response, just let me know.
Here is and example of the ID Map using red as the color "bound" to a given diffuse Map.
Are you sure need it to be an addon?
Otherwise you can use Compositor Color key node to create mask from color, and then color mix node to mask out textures: