For, with, of.

Three words—for, with, of—are the basis for a powerful grounding exercise for designers.

Oblique Strategies

Brian Eno and Peter Schmidt's Oblique Strategies holds up very well after almost 50 years, including its application to product design.

The D.E.W.-Line Card Deck

Marshall McLuhan made a card deck in 1969 that is a view into the times (the Cold War, let's watch for nuclear attacks sort of times).