My homepage video describes shows off this shape, amd describes how it was created (starting from one little cube, and following very simple rules!)
Youtube video:
https://www.youtube.com/watch?v=wxwvMNF_m2k&index=1&list=PLCTMeyjMKRkrhMSOf0SD677liIG6aaZ_3
Also, my website
https://sites.google.com/site/richardsouthwell254/home
has loads of free 3D printing resources (design apps & stls) on it.
This particular structure is very interesting, because it has lots of hidden details (chambers & such) which ca only be seen be peeking through the holes of the model. If one sliced the shape in half, a surprisingly elaborate interior would be revealed. Some parts of the model have a fractal form, but there is variation in different parts (like in the Mandelbrot set). This mixture of self-similarity and hetrogeneity gives the structure a strangle organic feel.
Again this object can be bought directly