I think if you poured that from the back of the skull there aren’t that many undercuts except around where the jaws meet. Still likely a 2 part mold but nothing overly complicated and putting the seam around where the jaws meets alleviate the undercuts there as well as helps hide the seam.

Or it could be a single metal mold utilizing the size difference after heat change to help release. Still poured from the back which we don’t see in the pics.

I do remember and I loved them. My child now has a subscription. Its very different these days but in many ways a lot better. They are made to be more reusable with activities and such and they have more specific age brackets for different content. Pretty great.

They were paid to do that

I had an experience like this camping out in the foothills of the Catskills. One of my favorite camping trips.