This is a claw, there are many like but this one is for blender. https://www.youtube.com/watch?v=JH5aF_mXaP4&feature=youtu.be
Any comments on what to improve are always welcome.
Usually a bunch of schematic drawings & then rigs. Most of the theory needed is taught in 'Humane Rigging' - a free course
Of course much of it changes now that we're going into the 2.8x.
Glad you like it.
really nice :D