The Dobot M1 is an interesting robotic arm capable of soldering, 3D printing, laser engraving, manipulating objects, and more. It supports Windows, Mac OS, Linux, and other platforms and is C++ and Python friendly. It has a repeatability of 0.02mm and speed of 200-degrees/s.
This video shows laser engraving with Dobot M1. The robot uses a pulse-width-modulated laser to perform line and shade engraving.