The real problem is getting the raw material.
Most of the stag was coming from India, and they have drastically reduced supply to prevent depleting the supply.
Some pros are using elk and whatever else they can find.
Some of the bigger knifemaker's supply houses stock some various raw materials big enough for pistol grips.
You work stag about the same way as bone, and bone makes both good practice material, AND good looking grips.
Seasoned cow bone works well.
You work it with jewelers saws and medium-cut files.
You have to watch power tools since you can cause cracks or over-heating.
Also, use a respirator or filter mask.