Vinny,
To make a complete pistol grip you will need a cam program to generate the code.
(Good grief I would hate to attempt to write the gcode.)
For my limited work, ( and i will assume that one side is flat) that would involve defining and drawing the profile and developing the surface to be machined. So 3D CAD with export to a stl file which is imported to a CAM program which generates the code. Now to add text to the grip on a curved developed surface requires addtional manipulation in CAD and machining steps. To machine the checkering is a challenge.
So in my case I am using AutoCad, exporting to Meshcam which generates the code for machining.
Enjoy the learning curve.....it will be a long one if your starting from scratch.
BTW,
One could make by hand and then lazer scan or surface probe as options to what was said above.
No I have not done any scanning or probing and will remark that they just add to the learining curve and cost.
There are other ways and different CAM, CAD programs out there that one can use.
RICH