try this.
use a mesh with high subdivision but it can cant have subdivision (levels.)
divide it a few time and then press tool>make polymesh 3D
now subd is gone.
MASK the area you want, the larger the brush size the wider the mask,
the smaller the brush size the thinner the mask.
then all you have to do is press tool>visibility HidePT
THEN use this combo slider plugin [http://www.youtube.com/watch?v=tJ9BvIdyjIE](http://www.youtube.com/watch?v=tJ9BvIdyjIE)
use the group loop slider and set it to 2
then once done CTRL+SHIFT the masked area
THEN use the two sliders on the right to extrude outwards or inwards
[http://i.imgur.com/koqOkHg.jpg](http://i.imgur.com/koqOkHg.jpg)

very important after you mask is to use tool>visibility HidePT
or the combo slider plugin wont work.
tip
if you want to use the lazymouse with mask you need to hold down CTRL and keep it held down then turn on lazymouse
