http://jenn3d.org/

jenn3d is an old freeware ( jenn3d_win_2013_06_20.zip ) .. it generates a lot of geometric structures some very nice ! some very complex !

works on any windows - the diameter of the elements can be reduced or enlarged
easy to use - the 3d file is named " jenn_export.stl " ... no choice ... so don't forget to rename the several models

01 jenn 02 jenn etc ... STL ... convert in .obj ( for example in Meshlab )

the parts are not joined so it's easy to delete unwanted tubes or spheres to keep interesting structures

examples imported in Max ... and with a remeshing in quads, the import in Moi is very quick