Dave M wrote:

These parts often have imbedded metal parts, such as a metal
ferrule inside a knob, or an imbedded nut or mounting tab.
Can 3D printers make such parts? If so, is any additional equipment or
unique model of 3D printers required?
If you want a nut in the plastic part, you can make a slot that allows you
to slide the nut in from the side. That would be the easiest way to do it.
If you truly want the nut embedded, I suppose you could make the build in
two parts, with a pause in between, where you drop the nut into a
hexagonal cavity. Then, the 2nd part of the build would cover over the nut.

Jon