Objects can be mental states, and mental states can be physical.
Paintings are physical objects. When I make a painting I try to follow this physicality as far as I can, starting with making my own paint from pigment and thinking very specifically about the stretcher and canvas. By really following the physical nature of a painting, the mind/body distinction can undermine itself, generating a concept that is a physical object, a painting we can use.
It doesn’t matter exactly what the painting looks like – it matters, but it matters to the painting, not to me.