I use to work in a foundry and ground casting flashings and poured iron at 26-2800 degrees. This will give you a basic understanding of how sand moulds are created to then be poured by molten iron. In the link they are doing what looks like car parts but trap parts are created very similar.
https://youtu.be/lvb_yarKK-8

Newhouse jaws. Pans and swivels are all castings

Here's a better one showing hand assembled sand molds

Why cast? Is it stronger?

Cast can be poured into the shape you want. Metal (steel) has to be worked into that shape. As in stamping, drop forging, cutting. Cast also does not rust away like steel does. Cast out lives steel. The first commercial trap manufactured by Oneida community out of nothing but steel was the "all steel". Few of those traps survive, especially in a nice condition. I've found a dozen or so over the years but not one had a readable pan. Some where so eaten by rust they simply went to the scrap pile. The traps where cheap in material to make and also where very light weight. Within a few years of first making the "all steel" victor traps would also become an all stamped out steel construction. The first few models of victors had cast parts.

Thanks good info