- In Blender Go in to Edit Mode and Select All of your Geometry.
- Press U or go to UV - Smart UV Project to unwrap your object.
- Go to the UV Editing Tab and Create a New Image for your texture to Bake on to.
- Set the File Resolution to something around 2k pixels.
- Go in to the Shading Tab and add an image texture for each of the different colors for your object - setting the image texture to your previously created texture. Don't Worry about Connecting this up to anything in the Shader Editor.
- Go to the Scene tab and make the Rendering Engine Cycles.
- Under the Bake section, uncheck Direct and Indirect Contributors to leave just the Color option.
- Set the Bake type to Diffuse.
- Press Bake to make Blender and wait for blender to project the UV colors on to the material you created.
- Be sure to save the resulting file, you can do this in the UV Editing Tab by finding Image* and then Selecting Save as.
- Check that the Color ID Map works by duplicating the object and adding the new image as it's own texture on the Object.
