Copyright can protect some invention design elements but in itself is unlikely to make any money for the inventor – with the unlikely exception that someone would want to publish the inventor’s notebook or make a movie out of it.
Inventors typically earn money through patents on their inventions. These give the patent owner exclusive right to features and processes of the invention, in return for paying royalties – a percentage of net revenues – to the inventor.
Although copyright doesn’t protect the functional aspects of an invention, it can protect its non-functional artistic elements such as pictorial depictions or graphics.