Prototype Lounge Chair Spider Casting Mold

This wood casting mold comes from the Eames Office at 901 Washington Boulevard and represents an intriguing moment in the development of the Eames lounge chair “spider”⁠—the cradling mechanism that supports the seat shell.

The finished spider, as seen on production chairs, was made of cast aluminum and is four-sided. At the Eames Office it was displayed on a wood plank with a handwritten label, The “Lounge Chair Spider Pattern.” It was made to be used as a pattern for casting the final form in aluminum.

This prototype represents an early structural idea: a central hub with three radiating arms supporting the shell. The shift from three to the final spider with four points on the production models marks a critical iteration. While a three-point system offers inherent stability, a four-point spider distributes weight more evenly across the shell, improving balance, comfort, and structural integrity.