In response to this discussion:
I am posting my definition for generating an open foam mesh.
(I didn't post back at the time because there were some troubles with weaverbird back then and I was having to use some ugly workarounds, but now that is all fixed)
To sum up the approach -
take a random cloud of points
generate the 3d voronoi
scale the edges of the cells towards their centres, and also towards the centres of the faces.
connect these 2 sets of scaled edges with mesh quads and join
cull some of the outer faces
subdivide and smooth with weaverbird
(In the video there were some other variations on the smoothing/relaxation, both of the initial point positions and the final mesh, using hoopsnake and/or kangaroo)