Hi Stefan, branching structures that are all smooth and melty at their junctures tend to be difficult to build with NURBS modeling. Structures like that are usually a lot easier to build with sub-d modeling instead.

You can sometimes use the technique shown here to do branches though:
http://moi3d.com/forum/index.php?webtag=MOI&msg=4388.55

But my main advice would be not to build that kind of thing out of NURBS geometry, sub-d modeling is better suited for that kind of shape.

NURBS modeling is strong when much of your model is defined by 2D profile curves and has distinct cuts in it. Your model there is not a form like that at all, it's more organic blobby with branches, that's where sub-d modeling is strong.

- Michael