This novel curiosity rattles when you shake it. It consists of 2 separate matrix of cubes with one printed inside the other. The smaller matrix is -3 the size of the larger matrix. The smaller matrix is not attached to the larger matrix. This is a uniquely 3D printed structure; it would be very hard to make without using 3D printing.

The printed Captured Cubes in the photo is size 6. I've provided stl files for size 10, 6, 5, and 4, but you can make the size you want with the OpenSCAD source file.

Removing the supports for the internal cube is a bit tedious. I found that my manual supports are easier to remove than the supports that are automatically generated. The OpenSCAD program will generate models with or without manual supports. If you choose to use automatically generated supports, check the boxes for “build plate only” and “don't support bridges”.

See: https://www.printables.com/model/188695-parametric-many-cubes-scad