How to make the arms of a rigged character slide on the surface of the body

Question

So I saw a pretty good rig the other day of an egg shaped character, but what caught my interest was that when you move the arms around the body (from the shoulder), it seemed that the arms where attached using a boolean modifier, so you could have the arms move to the front of the character and the mesh still looked great. I don't have access to this rig and it was made using maya (I think) but I wanna try making the arms effect on blender on another round shaped character. I tried using booleans but it always created some artifacts, that makes me think that the original rig wasn't made using booleans. Any ideas how to recreate this?

Here goes an image of how the arms moved. Even when moved, the arms still looked like they are coming out of the body, not like it was just another object. And here is the model that I want to use to recreate that effect.

Answer 1

For Cycles, a trick would be to use a distinct mesh for the arm and use the Bevel node. It will create the illusion of bevel where the meshes are joining, so you'll be able to move the arms however you want and they will still be looking like they are part of the body. Keep the Radius value low (here 0.1).

In Eevee (or Cycles) you could try with a large topology around the arm joint so that it has latitude to move. Give it a Shrinkwrap modifier with a sphere as Target so that it stays spherical:

Or you could use the arm as a distinct object and try the Shrinkwrap modifier, with the Wrap Method > Surface and with a group assigned where the arm is supposed to stick, but it looks hard to get good result: