Before making them in wood, I made these models from black and grey textured paper. As the image shows, they are mirror images of each other.  Each has the property that if you switch light and dark regions, they remain unchanged.  And if you promise not to like them any less, I will mention that they also illustrate an interesting theorem that certain topological operators commute. Each is also color-symmetric with itself in the sense that they are congruent to themselves if you switch light and dark. This paper gives some background about the geometry.