Hello, fellow Hearthlings & hopefully our god Loftrb!
I am here to suggest that we could apply paint (that is used for making sketches) to the variable material slots of... well, anything. From furniture to houses - where it makes sense! So I'd probably not allow to add it to thatched roof.
As an additional chefs kiss would be to create & allow to apply carvings to wooden and stone structures with various nordic patterns. Oh, and it could also be a fun thing that if characters with low carpentry or masonry skill trying to do that would fuck it up and make an eye-sore of a pattern!