3D prints vs Manufactured at scale

I'm hoping to concept and 3D print some chess-like miniatures for my game. Gonna dream big and ask, what should I keep in mind for a clean transition to Manufacturing 1000+ copies?

How do manufacturers typically handle game components. I've heard that many will work with you to realize a proto-type. Is that still the case with the advent of 3d prints? Do a lot of Manufacturing companies use 3D printing or do they use molds of some sort?