Designing an unusual 3D model

Dear all, I’m a university student in charge
of developing a biochemical device (reactor) for the depuration of
leather factory wastewaters, this is an european project leaded by
Ambiental Engineering University of Florence. Part of this device should
be colonized with fungi in order to purify water, and they (the fungi)
need a biodegradable material with a certain porosity to grow. I am
currently developing a tester sample and I’m going to 3D print it in
PLA. The tester should be as similar as it can be to a small cube of
"low density polyurethane foam" ( 00_85/241590_1_pu-filterschaum-schwarz.jpg).

I was thinking about using some algorythm like voronoi, but I’m not sure it is the best option.

What do you think? How would you make the 3D model?

Ps: I’m quite used to nurbs modeling, but not so much in poly. I guess the latter method is more suitable, am I wrong?

I think this thread should be of interest to you: