My sister in law was wondering about painting a peace sign on my torts she'll. I told her no because of the toxins and it might kill him. Thought I would ask for a second opinion?
There is animal safe paints. Some put a mark to ID between torts. However, only the very top of the scute could have this done, not in between the scutes. I personal opinions, no animals should be painted on. That's not what they were meant for. I also don't approve of the animal dyes people are using on their animals either.
By way of personal opinion, I don't think it's a good idea for aesthetic reasons. You can certainly find paint that would be non-toxic and some people do things like this, I think it takes away from the beauty of the tortoise.