A train layout is NOT the same as a swimming pool; Sorry there is value to a pool, or a new remodeled kitchen, or a new powder room or a new roof. Nada for a train layout no matter how well built or detailed or in a magazine or video. It's unappreciated or under-appreciated artwork.
Most buyers look at it as a "choo-choo" and would rather have the space to store old tires!
EXCEPT if one of us buys one of your houses with a layout well that is a different story.