The Menger Sponge is a 3D fractal that is constructed from a cube. A level 0 Menger sponge is simply a cube. To construct the nth-level menger sponge, we divide each section of the (n-1)th-level menger sponge into 9 sections, like a Rubik's cube. Then, we move the center face, creating a hole that extends through the entirety of the Menger sponge.
This Menger Sponge is created dynamically from a python script. The python script is fully parametrizable, allowing one to change the length of the base cube side and the which level Menger sponge to construct. The script uses Blender to generate the STL file from a list of points and faces that it constructs, and also uses Blender to make sure the STL file is correct.