http://www.scortea.at/index.php/portfolio-3d_totenkopftasche-19 << there you can see some pictures of how i did it.
the molding part is quite easy if you know how....and there are two ways i use:
1.) you take a thin piece of leather, put it in hot water for a couple minutes, wrap it over something which has a round shape. now you will have the basic shape of the head, then take some plasticine (plastilin in german) and put it inside, this will help you keep the shape. now add the details with your fingers or small rounded tools, i just used the back of some pencils since these are rounded and got a smooth shape so you dont scratch on the leather.
2.) a lot easier. you can wrap it over something which already has the form you need. either you take a little toy which is not to filigree for this or if you are skilled, mold yourself something out of clay. another good point on this one, you can use it over and over again and it saves a lot of time.
hope it helps ;-)