I replied to your topic about China stopping exports of stepper motors and aluminum extrusions, now you're switching to yet another goalpost.
For what it's worth, I've spent a lot of time with 3D printers in the past decade. The amount I've learned doesn't hold a candle to any of the deep dives I've done for real engineering work. A couple months of paid full-time engineering work on in a new area would bring any engineer up to speed.
3D printers are cool, but the self-importance some people attribute to this hobby is a little too much some times.