The figure is
See the how-to video
https://www.youtube.com/watch?v=vln7rc5WYWM&feature=youtu.be
the how-to video or a speeded-up gif
http://i.imgur.com/GO22Mqr.gifva speeded-up GIF.
I believe it should be possible to draw this figure programmatically using some Random
function, but I'm rather new to MathematicaMathematica, so I could really use some help here.