Modeling settings or Weld on prefabs?

I am new to jewelry production and could use some advice. As I work
on some designs I am wondering how I will attach the gems. I want to
use some small gems 2 - 4 mm. in singular settings. For the current
designs I am working on I would like to use prong settings. I am
wondering about the feasibility of casting these very small (IE. 2-3
mm round) prong settings as part of the ring or does it make more
sense to tack weld and or solder them on separately. I am doing the
designs on the computer so I could model them, but having to pull
them out of the mold in wax with the ring seems tricky since they are
so delicate. And I have noticed that the die struck settings of this
size actually have the prongs bent to form a bearing, this style
could not be molded I think because it would crate a undercut.

Thanks for any advice,
Bruce.