You model one element of the structure as a solid, then pattern that as a 'body' in x,y dimension, then pattern all those bodies in the z dimension, then 'combine' all the bodies.
Do you have any idea how to make a "organic" strucutre like this?
Looks pretty straightforward once it's pared down to a single repeating element. I'd have to be more familiar with the geometry to say for sure 'here's how I'd construct this or that'.
In the picture it looks like some kind of skeletal polyhedron patterned x,y and z. I'd probably try to construct a wireframe sketch (multiple sketches actually, unless you're really good with 3d sketching) of the single polyhedron first and build the solids from that.
Word of warning, large patterns with many instances can quickly slow things to a crawl. Strategically combining as you go can help to a degree.