• if you know the key code or bitting code for a key, you can have a key manufactured to that specific code
• but how do you manufacture a key for a specific code?
  • computerized code machines (quick and easy, but expensive)
  • depth keys
    • the actual process is detailed on page 31 of this PDF
  • hobbyists usually just file down their keys, since that's much cheaper than alternatives. There are some tips on filing here.