Typically, the designer is invited in at stage 6, product development, when the prototype product is to be developed. Designers, however, should be brought in earlier, preferably in the idea generation stage or at least the concept development and testing stage. Designers are capable of producing ideas that no customers would come up with in the normal course of researching customers for ideas. And, during the concept development and testing stage, designers might propose intriguing features that deserve investigation before the final concept is chosen.
