generative modeling for Rhino
If I would like to draw a tower like this (below the picture) what type of plug-ins and strategy I should have?
it's kind of an open-ended question. Especially since those two images aren't much alike. Maybe you could use Kangaroo with sticky-forces or something to wrap the shapes with strands. Maybe you get better results with a recursive instead of iterative method. Either way, Rhino+Grasshopper don't seem like the obvious choice for this kind of geometry, a good voxel/mesh/particle editor will probably make your life a lot easier.