Below is an image from a program called google SketchUp, click here for more details on the program.  All sides of the object are equilateral triangles and it is self-similar, thus fitting the definition of a fractal in the simplest sense.  The two parallel lines entering the structure represent rays of light or sound traveling perpendicular to the ground and where they are directed after they enter the structure.  I think the next step is determining where more rays would go if they entered the same opening at different angles.  I’m looking for some free or cheap ray tracing software that would let me import the model as an AutoCAD file and run some rays through automatically.