Hilbert Space Filling Curve

The Hilbert Curve is a space filling fractal curve. It is a recursive process that eventually fills the entire space using one continuous line. See https://en.wikipedia.org/wiki/Hilbert_curve for more information.

This thing holds the STL-files for the first four recursion levels. Although normally the outer space of the cube is held constant, I decided to keep the length of the line fragments constant such that it can be well printed at all level. One could manually resize the figure if one