Random

Hello,
I'm trying to create a sponge-like geometry (see attached AluSponge.jpg). I thought about randomly positioned and sqeezed spheres to subtract from an outer geometry. In the beginning I hoped that a [Rebuild solution] would mix up positions and squeezings in a new way. But [random] and [series] don't work that way. I tried using [random reduce] with variable Random Generator Seed Value (see attachement), but it may be feeded different...
How can I build a random number generator in GH? How can I make it re-calculating other random numbers? Should I try a completely different approach/modeling route to arrive at an sponge-like GH-definition?
Thanks for every hint! Philipp