Is there a way to extrude cut from a surface?
Hi, I'm trying to model the internal surface of the mouse http://h30434.www3.hp.com/t5/image/serverpage/image-id/53769i14FB8210D5BCAA52/image-size/original?v=mpbl-1&px=-1, I have this model which I've solidified because the rest feels solid:http://imgur.com/5nZxPh7 but I want to extrude the top surface down and cut out the material between to make the inner surface. I know you can offset the surface like this: http://i.imgur.com/O3Pw4OC.png but I cant figure out how to remove the material between.

