sculpting question

hello, all.
I have a question about sculpting.
I would make nose-gates and have the shape but now i want the nose gates.
But i only see at the sculpt mode a option that it will tear the object outside but i want now it will work inside so when i sculpt on it (turns rounds) it will go into the object and not going outside?
Which option do i have to select then or how to make other nose-gates.
Thank you for help already.
PS. i use blender 2.56.

not sure if it’s what you’re trying to do, but holding ctrl while sculpting uses the tool in reverse

Ty, it works.