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. It's hard as it's so tempting to recreate the Tomytec markings in paper!