robot sketch by darkzside.deviantart.com on @deviantART
Excellent series of artwork by Utah based Jake Parker - best known for his Missile Mouse graphic novel.
Croquis de robots / Sketches of robots
Robot Sketches - looks like the robots from Machinarium.:
Sketch of a Robot by designer Spencer Nugent
Genos arm reference - One Punch Man. Because robot arms are hard to draw.
robot sketches | Posted here: www.san-smith.com/2011/03/art-… | Flickr
Robot library https://www.facebook.com/CharacterDesignReferences
Project 2: Robot Design - similar sketching technique (plan to keep for finals)
*Inktober* Robot Sketch, Jae Cho on ArtStation at https://www.artstation.com/artwork/gwyyx