Don’t forget about things like art and books.
There are so many awesome books from the 1920’s-1950’s I’d love to read, but I have a lot of trouble tracking down a copy of, even after combing through ILL, eBay, Amazon, and all the other used booksellers.
But because you’re not quite sure if the copyright was renewed (28?) years after the first 28-year period, you don’t know what would be fair game or not in trying to resurrect with a new print run. In theory, something from 1945 would have entered the public domain after 56 years, in 2001… but you don’t casually mess with other people’s intellectual property.
For example— I have a book here at my desk that was originally published in 1946 by Doubleday. Then Doubleday reissued a new edition in 1976, 30 years later. Is it in the public domain? Is it still under copyright? Does the author’s estate still hold the rights to it? etc, etc, etc.