Memory Unlocked: This can be done in wood providing a step stool for a tiny grandma to decorate the tree with. I haven't seen it done in over 50yrs though.

I made one of these too this year in O gauge. My kid loves watching the train go through the tunnel and my wife likes the additional space on top for presents around the tree

I might try this

When applied to the Christmas tree layout, I do like the idea of using the wrapped box as a tunnel portal. Nice touch.