This is a 3D version of a Menger Sponge, traditionally made with business cards.
This is a Level 1 sponge, which forms the basis for more complex sponges.
This is a Level 2 sponge. As you can see it’s merely additional iterations of a Level 1 sponge.
Now you could take this and turn it into a Level 3, that into a 4, to infinity…AND BEYOND! 