Forensic facial reconstruction is where someone tries to figure out what a person looked like based on their skull bones. When someone dies and their body is found, sometimes they don't know who the person is because they don't have any identification. So, forensic scientists can look at the shape of the person's skull bones and use that to make a picture of what they think the person might have looked like.
To do this they start by looking at the skull carefully and measuring it to figure out how big it was in different places. They then place markers all over the skull so they can figure out where the features of the face were, like the nose, eyes, and mouth. Once they have an idea of where the features were, they start adding clay to build up the face. They keep adding and changing the shape of the clay until it looks like a realistic face.
After they have made the clay face, they can add things like hair and skin color to make it look even more realistic. This can be really helpful for figuring out who someone was, especially when there is very little information available.