I do not see an easy solution. In sections for example you could use a region. But it would not be visible in a 3D view
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If you would need it in 3D, depending on the accuracy you could model a family and just place it in the model
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You might need multiple of these lements to cover an area depending on the elvation differences.
This can aslo be done in combination with the paint tool (e.g for walls) where you can split the face and then paint that area.
Other solution would be to modify/create door models where the shape is built in so you can just use different materials.
But depending on how many areas you have to do and on what level, it will be quite labour intensive.
So also consider not modeling it and use detail drawings to show design intent. Alternative way might be creating renders and then use photoshop (or similar) to colour the areas.
Louis
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Please mention Revit version, especially when uploading Revit files.