During the creator's commentary in Portal 2, Valve animator Richard Lord called the eye portion of loveable personality sphere Wheatley's design a physical impossibility. Cosplayer Furin's talking Wheatley puppet seems to have done well enough.
After Portal 2's release made her switch gears from her planned Fullmetal Alchemist cosplay for this year's Dragon*Con, cosplayer Furin switched a few gears of her own, transforming Valve's brilliant though admittedly-flawed design into a living, blinking, and quipping machine. She's managed to capture all of the personality voice actor Stephen Merchant and animators like Lord (the original voice of Wheatley) instilled in the glowing mechanical eyeball in one conveniently portable package.
Furin will be making an appearance next month at Dragon*Con in Atlanta, Georgia, so I might get a chance to drool over Wheatley in person. Hit up the link below to see the hours of painstaking work she put into creating this most human of machine "intelligences".
Wheatley [Furin Cosplay - Thanks Tim!]