ArtStation - Sculpt - Practice 1, Alexander Fuhr
Zbrush dynomesh sketch that was rendered in Modo. Lots of material passes that were then comped together in photoshop.
The art of Jens Fiedler
Rockerbot Re-rendered, KEOS MASONS - Marco Plouffe on ArtStation at https://www.artstation.com/artwork/NzDX1
ArtStation - Ghost in the Shell - Hunter Droid, Adam Middleton