This filter uses recursion to create cubic (or rectangular prism) wire-frame nested structures within your selection box.
The algorithm starts with the perimeter of the selection box, drawing the cube. It then considers each octet of the cube and randomly decides whether to draw a smaller cube within. If it does, it calls the cube handler with the smaller volume, which itself examines each octet (and so on). The process stops when the cube sizes get smaller than a limit.
This is a modified version of my WEB filter.