Wandel is really cool. Highly recommend his woodworking channel. Some of my favorite things he's made cluster around making high precision things with tools that are usually easy to use imprecisely.
Copy Carver - kind of a manually run 3D CNC, lets the user 'trace' in 3 dimensions:
Pantorouter - build an oversized template, then end-cut a piece in a way that scales down that template (effectively multiplying precision of the template to achieve precision you wouldn't be able to get otherwise)
These are amazing. I could swear I've seen some of an horizontaly, not vertically, mounted pantorouter.
Since discovering the pantorouter for woodworking I always wondered: wouldn't the same technology make sense for ultra precise 3D printing at home? Instead of having the motors drive directly on top of the model, have the motors drive a pantorouter instead and have the smaller end of the pantorouter on top of the model. It's "just" simple machines right, lever and axle basically?
I would think that play would be difficult to keep low enough to make this worthwhile. A servo driven hot end is already pretty precise, so a pantograph-like transfer would have to be rigid and tight enough to beat that. No small feat.
Here's Stefan Gotteswinter giving a talk about his Deckel G1L pantograph engraver.[0] For the side load on a 3D printer it probably would work fine but as others have mentioned, 3D printers are already relatively precise. 0.04mm/step on my ender 3 as I recall. (about 1.5 thou)
Copy Carver - kind of a manually run 3D CNC, lets the user 'trace' in 3 dimensions:
https://www.youtube.com/watch?v=LyNu8lpQI1g
Pantorouter - build an oversized template, then end-cut a piece in a way that scales down that template (effectively multiplying precision of the template to achieve precision you wouldn't be able to get otherwise)
https://www.youtube.com/watch?v=J_72hOY2vPg
https://www.youtube.com/watch?v=qUJzuM3PRAI