Mach itself dosen't have a "magic wand" to do what you want to do. There are some options you can consider and time management is a decision only you can make for what you want to do. As Hood stated i also believe that having it in CAD gives you manny options.
One consideration is accuracy of reproduction since it makes a big difference in how it's done.
- CopyCat can trace the pattern, large or small, and would provide the gcode. You backplot the gcode and end up with a CAD file.
You will need to use your machine along with a WebCam ( cheap ......one), but most important is using something like the XBOX 360
to help make tracing the machine movements easy.
- You could also use photography to get the image and then procede in a number of different ways.
Quantity, size, accuracy, cost, etc all come into play.
BTW, for me at the hobby level, usualy one of a kind, rather small but could be complex,accuracy is very important, and time is not a big factor.

RICH