Crisp edges on subsurface modifier Im trying to figure out how to make crisp edges on my mesh, without using loop cuts, which affect my  mesh. As seen in the example on top of the model, I deliberately added a bump and on the side, I extruded a section inwards. Now when I add the loop cuts to give it a more crisp edge, the loop cuts which go around my model, also affect my object making it to deform. I tried the Edge Crease method, but the extruded section remains like a circle shape, and not rectangle which I'd like. Any suggestions how to get a particular section more crisp with out affecting the rest of the mesh? 

Thank you.
You can inset the 3x3 faces that surround the one you've extruded instead of extruding it. Once inset done extrude the inset.

Then add a loop inside of the hole to sharpen the borders: