Dolphin Dictaphone

To create culture one needs a way to record. Just like books changed civilization people, could recorded history create culture revolution for dolphins?

And, if dolphins could pay for microphones with their intel, maybe people could trade with them.

Could start with stationary (library-like) items.

Later, could be a strap designed, like a cloth, that can carry on front fins, and charge with water flow. (Think - mobile phone for dolphins.)

However, if by an chance, the humanity were to disappear, the poor dolphins couldn't make those devices. Therefore, it would be great to get them become independent, and have factories in their water... This is a challenge of a different level, even for humans, how to get dolphins be able to manufacture something.

People could communicate with them over the Internet. But the more interesting use case would be to learn their language by observing, what recordings will they make.