Summary

This is a 5th order Sierpi?ski curve extruded along the Z axis.
http://en.wikipedia.org/wiki/Sierpi%C5%84ski_curve

Instructions

I modified a BASIC program from the July 1984 edition of Creative Computing magazine to run under Chipmunk Basic on my Mac.
I modified the code to save a text file with the coordinates for each line's end points.
I then created a blank SVG file with Inkscape. I opened the SVG in a Sublime text editor and created a polygon with the coordinates from my program.
I then loaded the SVG file into Inkscape and exported it as an Open SCAD file. From there I exported it as an STL file.
You can find the original BASIC source code here: https://archive.org/details/creativecomputing-1984-07

BASIC source code and rudimentary documentation is included.