Proof and evidence will always equal Science

[Ferrocyanide]

I'm probably going to regret asking this, but are you saying that metaphysically speaking, chairs aren't evidence for the existence of chairs because physical evidence has no bearing on metaphysics?

I suppose so. A metaphysician wants to know what makes the chair a chair. It's "chairness" so to speak. You won't find "chairness" out there in nature. "Chairness" is completely conceptual... not a physical thing... hence "metaphysical."

You seem to be talking about design in this case.
A design (blueprint) is not a physical thing. It is not made of atoms.
But the actual chair is made of atoms. The collection of atoms is a representation of a chair.

Instead of calling it design, you can call it information as well.

Words are pieces of information as well. They aren’t made of atoms.
However, you can take some ink and put it on paper and you have a representation of the word. The ink and paper is made of atoms.

Music is also information. It is non-physical.
The cassette is a physical representation of the music.

Stories in books, musics, the blueprint for an airplane, a circle, letters and languages and basically anything has a design component and a physical component.

Do stories exist? I would say yes and no. It depends on how you look at it.
Maybe it doesn’t exist as long as it isn’t written on paper or in the mind of a person.
Normally I say no to make it clear to people I make a distinction between information and reality (atoms).

Does a god exist? Yes, in the minds of people. Smurfs exist in the minds of people as well.

The physical reality is very different than a social convention about what is and is not a chair, let alone whether something that is typically not  chair is used as one on some occasion.

For a social convention to exist, you need a population of humans and humans are made of atoms.