This tutorial that i really love to share it is pretty good tutorial. The First one will explain the basics of how to make 3D indents in photoshop, the second one is how to make advance form of it and the third one is mastering. ( this tutorial is taken from
effectica )
The Basics
little more basics
after you know a little try this one...
Mastering
Edit : Please show me something if you try to make one

.