Solidarity responsibility
Protecting yourself from responsibility for mistakes by blaming your partner in case of failure or, in case of success, by attributing it only to your merits is nothing to boast about.
Common objective of the producer and designer
It is a chance to optimize production adjusted to the tools and technology park the producer has.
Prototyping
It refutes the too-often-applied saying connected to designers “You can write anything you like on paper”.
Non-obvious design values.
Establishing social relationships takes place naturally.