In the 1960s, artists affiliated with the Fluxus movement bypassed the gallery system by mailing each other portfolios as boxed "exhibitions." Collector William Copley set up SMS, one of the more famous of these exchanges, which brought together an assortment of surrealists and younger artists: Oppenheim, Ono, Cage ... Duchamp, who designed the covers and table of contents of one of the six "issues" in an echo of the "rotoreliefs" he'd created four decades previously.
An entire set of SMS is now on display at the California State University-Long Beach Art Museum.
(Through April 18. The CSULB Art Museum has details.)