I came across a builder of wargame modules who has over 400 videos. He has a lot of 'how to' with materials and substrates that would be applicable for model railroaders. A few links are below:
Foilage - https://www.youtube.com/watch?v=uj1q1hK-9qk
Foilage - https://www.youtube.com/watch?...rKMTHT2wEevSlanLf69f
foamboard - https://www.youtube.com/watch?...rKMTHT2wEevSlanLf69f
Blue HD styrofoam - https://www.youtube.com/watch?...rKMTHT2wEevSlanLf69f
He has a whole lot more.
Joe