Copyrights should expire much, much faster. Five to ten years would probably reasonable. In its current form, copyright is an obstruction to the creativity it was designed to incentivize.

Various studies put the sweet spot at about 14-15 years.

While I think current lengths are too long (they are virtually unlimited) they do nothing to obstruct creativity that it was designed to incentivize. Copyrights were designed to encourage the creation of original art, not derivative art.

The irony is great. Readymade art, remade in the 3d printed world. ReadyRemadeAndReprinted art as it should now be called. All the 3d printers need to do is sign every piece and hang them in a museum .