I have created this Pushpad device used to a handle assembly, I now need to shell the underside so that the thickness is 1/4" thick, the Shell feature won't let me do this, and I have tried a couple other strenuous yet failed attempts to get around this, any suggestions? The Blue area is the area that is to be shelled. As you can see the curvature of this piece makes simply using cut extrude to shell it out manually.