Sketchbook by David Ngene, via Behance
Jean-Rene Caillette, Croquis de 21 pièces de mobilier datées de 1949 à 1986
rendering plastic with pencil - Google Search
This sketch is credited as belonging to "Stefan" - if anybody has any more information please let me know! :P
Flex Table by Joshua Welt, via Behance.
Sketching: for years tried to have a rule to make a 'sketch a day', this is a great example how it should be done! It probably took only 15-20min (if that)!