How about a motorized 1:1000 scale Toyoda AA?
https://japanesenostalgiccar.com/the-worlds-smallest-car-is-a-toyota-aa/
In all seriousness, there are some nice etched brass 1:160 kits that I have seen built very cleanly. I've had thoughts of detailing the tiny trophy topper that came with Revell's Mercury custom. ?
If someone can built microscopic models, let 'em. It would at least be entertaining for the rest of us. ?