Yup, pretty much the universal problem. It's highly skilled work that doesn't pay great, as is resin casting well.
Far as casting goes, you need to have a broad enough product line so that something's always selling if you want to even think about making a living at it. That takes a whole lot of up-front work in masters and molds, and after all that, the products you like may not have much market appeal.
Then there's the growing problem of being unable to find help that has any kind of physical skills, or interest in learning any.
But out of 330,000,000 people there's not even a few?