Carbon Brake Disc , The  Gear itself i received it broken but i was able to fix it with my angel Grinder and My Arc Welding Skills , then i start by scanning the gear with my A4 Scanner to get clear photo from the profile of Teeth and i Cut Wood base to Test the Gear .

The Goal to Cut through Carbon Brake Material and the Gear must fit inside .

The Material Is Very hard and will break the Endmill Without Good Cooling . it need Specific Shape of Endmill and it must Be carbide otherwise it will not too long . i made simple water path for the dust and i started by cutting the internal Gear and then i checked that the gear fits perfectly then i start to cut the outside of the material.

Note : your CNC must be Closed Machine like mine , the Carbon Dust is very Danger and can irritate the lungs and cause coughing