Commercial Printers:

https://www.creality.com/

https://www.prusa3d.com/

https://www.geeetech.com/

https://sovol3d.com

https://www.tronxyonline.com/

Opensource Printers:

https://vorondb.com/

https://openbuilds.com/?id=272

https://reprap.org/wiki/RepRap

https://vorondesign.com

Filaments:

https://us.polymaker.com/

https://www.hatchbox3d.com/

https://www.formfutura.com/

https://www.esun3d.net/

https://colorfabb.com/

https://www.proto-pasta.com/

https://taulman3d.com/

https://www.prusa3d.com/

Learning:

Services:

Software:

https://slic3r.org

https://octoprint.org/

https://ultimaker.com/software/ultimaker-cura

Models:

https://Thingiverse.com

https://Thangs.com

https://Printables.com

https://yegi.com

Manufacturors:

https://e3d-online.com/

https://store.micro-swiss.com/

https://www.sliceengineering.com/

https://www.igus.com/