Tube shapes, knurled ends, threading (like on a screw), the checkering you might see on a metal dentist tool - all of these are achieved with a lathe and different tools. The aforementioned gouge, checkering tool, threading tools and more are applied to the spinning material of choice and something new is born. The lathe can be used in a very simple way to create simple turnings, or for the more advanced user it can be used to create highly complicated and intricate designs.
Up next is the milling machine, and I won't even kid with you all here - this machine is complicated to use! Aside from controlled drilling, even I stand in awe of its abilities to create and the technical know-how needed to do it. So now that I have proclaimed my mere amateur abilities with the milling machine let me tell you what trial and error and research have shown me.