This is a model of an NaCl unit cell in the scale 1: 10-9. Both unit cells fit perfect in the ionic lattice model: https://www.youmagine.com/designs/nacl-ionic-lattice-version-2 In the new version 2 (update june 2023) of the lattice the spheres overlap, are more rounded and cut off at the bottom. This model and other educational examples can be found on the Erasmus + project website: make in class: https://www.makeinclass.eu or the website of the Gymnasium Neubiberg https://www.gymnasium-neubiberg.de This thing was made with Tinkercad. Edit it online https://www.tinkercad.com/things/jfMBQXIERX9