Here’s what Andy Hertzfeld, an original Macintosh team member, told Steve Jobs biographer Walter Isaacson about the design process: Chris Espinosa kept refining (the calculator] in response to Jobs’s critiques, day after day, but with each iteration came new criticisms. So finally one afternoon, when Jobs came by, Espinosa unveiled his inspired solution: „The Steve Jobs Roll Your Own Calculator Construction Set.” It allowed the user to tweak and personalize the look of the calculator…

Instead of just laughing, Jobs plunged in and started to play around with the look to suit his tastes. After about ten minutes he got it the way he liked. His design, not surprisingly, was the one that shipped on the Mac and remained the standard for fifteen years.