This is a design to print a tetragonal prism and dipyramid form. Crystallography classes can use this print to help visualize what the crystal looks like. The visualization also teaches about the symmetry of the crystal. This print is a physical manipulative than can be used to teach these concepts.
This is a much better alternative to models that cost $100+ (https://www.miramodus.com/molecular-models/beevers-models/alphabetic-index.shtml).
The blender file needs some fixing. However, the stl file is fixed with the help of netfabb and prints well.