How I can make a "rubber-line"?

Support Basics & Interface
1

How I can make a “rubber-line” in Blender?What method i must use to make that line like on pictures down?

http://www.abbys.hu/Tutorial-Boxmodeling/Chapter08/snap009.jpg

http://www.abbys.hu/Tutorial-Boxmodeling/Chapter08/snap011.jpg

http://www.abbys.hu/Tutorial-Boxmodeling/Chapter11/snap007.jpg

How can make that creases and edge ?

2

http://img106.imageshack.us/my.php?image=snap007ff4.jpg

http://img171.imageshack.us/my.php?image=snap011hm0.jpg

http://img171.imageshack.us/my.php?image=snap009zn5.jpg

3

http://mediawiki.blender.org/index.php/Manual/Curves