I have a sim who is secretly a robot and though they are indistinguishable to a human sim, I'm thinking of what if they have damage and some of their parts get exposed like maybe hollow scars or scrat...
If you have pictures of what you want the guys over in this thread may be able to create something for you: https://forums.thesims.com/en_US/discussion/959098/i-take-cc-requests#latest they are a couple of wizards!