It’s just my own oppinion, but as far as I can see, the expression “3D printer” is somewhat restrictive due in principle it is assumed the extrusion or any other additive process to fill regions with materials. Most of the knowledge base as well most of the electro-mechanical structure used for that may cover a wide range of other subjects related to equipment working in the 3 dimensional space, such as milling machines, CNCs, pick-and-place, etc…
Perhaps the already existing “Robotics and Automation Forum” is the best place for discussing that subject.