- a separated mouth with an inner part parented to an empty
- a vertex group for the lips far border (see attached picture)
- a shrinkwrap modifier to stitch this group on the character face
- a data transfer modifier to copy the normal face polygon normal orientation on the vertex group
- a parented object to the empty that ll be used to boolean cut the face where the mouth is.
Bool_mouth.blend (796.6 KB) blender v 2.93
You must be in Material preview or rendered to see the corrected normals sticked on the head