Hi!
We just joined DIAMAS as diamond OA publisher. CEUR-WS.org is run by a group of computer science academics from various universities and research institutions. It is hosted by the Technical University of Aachen (rwth-aachen.de). The first volume was published in 1995. We now publish around 250 new workshop proceedings volumes each year from all over the world.
Since the beginning, we did not collect any fees, thanks to the voluntary contributions of the editorial board and the support of Informatik V at RWTH Aachen, who kindly host ceur-ws.org on the SunSITE Central Europe.
We are curious to share experiences with other grassroot diamond OA initiatives!
Kind greetings, Manfred Jeusfeld (founder of CEUR-WS.org)
PS: More on the history of CEUR-WS is at https://ceur-ws.org/ceur-wspresentation2019-10-02.pdf