Help with Bowerbird - deeper value?



I am playing now with Bowerbird plugin and have some questions:

  1. How to make negative value of deeper connection. I have some problems with my small parts and I need to have shorter indent and i can make only longer.
  2. Is there any possibilty to different thickness of the material? For example i want to have middle part 2 mm and the rest 1 mm. Something like that