Normally this requires an involute gear cutter(or hob), of which there will be several for the same Diametrical Pitch value, as the profile of the cutter needs to change a bit due to the number of teeth. You can also grind a peice of tool steel to make a form tool and use it as a single point cutter. OR if the tooth profile is large enough, you can use a properly sized end mill to cut the gear on a 3 axis mill. However this would likely be a very hard thing to accomplish(in something other than plastic / wood), for reasons I wont go into here. So, if you have a 4 axis CNC or a manual mill with a dividing head, or rotary table look into the involute gear cutters.
If you want to search around some, another word for gear cutting is hobbing.
Here is one example
http://www.youtube.com/watch?v=VHTXa...eature=related
and here is another, using a different style cutter
http://www.youtube.com/watch?v=62yme...eature=related