An industrial designer, unlike a sculptor or painter or photographer, must rely on upon a manufacturer to make their ideas into objects. The give-and-take between a designer, eager to retain the integrity of his ideas, and a manufacturer, keen to simplify and economize the process of producing the design, can be a frictional relationship. But it can also result in improvements and refinements to the design and to better products. Castiglioni had a long and fruitful relationship with Italian industry, working with most of the major Italian companies and in many cases greatly contributing to their success and prestige.
Following is a list of the major manufacturers that Castiglioni worked with over his long career, with links (where possible) to their websites. Also included is a small list of sites that retail some of Castiglioni's objects.