This figure might look nicer in wireframe, without colors or shades, as surfaces turn into nothing after they’ve gone behind what is up front. (Which is available now. Check the Linework link below the image.) I’ve tried to show this by adding gradients that fade away. Notice how the lines that seems to just vanish behind the bars end up being part of something else. I have a few personal principles I follow, like how I don’t just leave a line hanging somewhere, they have to connect to something.
In the middle one surface is facing right at the top and left at the bottom. At the same time surfaces flip around one of their edges when passing behind other parts of the structure.