- You need to find any model you want
- Use the original GTA V model to make it as reference like if you want to rig cap, use the original GTA V cap to make it as reference (like the position, size, etc.) or you can use head model of Franklin or Trevor or Michael to make sure the cap is fit with the head.
- After you have satisfied with the position and size of the modded cap, you need to attach the cap with the original GTA V cap.
- Then you can delete the original model of the cap.
I assume you already have the knowledge on how to import ydd into 3ds max.
If you want a detail tutorial, find it on youtube..