Re: making a stock
The beauty of making your own stock, is that you can customize it to your hands. If you have a thumbhole stock to use a reference, then I would take a few measurements on where they have the actual hole. Mill in the pilot hole and then shape it from there. Remember, you will need to remove material in order for your hand to rest at an angle. While you're at it, a small palm swell may be in order. A round bastard file will remove material well, as will a 1/2" drum sander on a 1/4" die grinder...
"Character is who you are when nobody is watching"