More stuff for you Andrew, I just keep stumbling into these gems - here are diorama bases from no less than Tomytec themselves, who make those 1:150 N gauge vehicles and houses:
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I think they're meant to fit inside a clear display box, but it doesn't mean one can't repurpose them - I think the display bases for the buildings might be too small for 1:150.
I am making progress with my bonnet truck kitbashes of the Kohnan Electric buses, and am trying to keep everything unmarked so builders can customize them to their taste.