I'd like to print on Obarun. But my print settings are looking for the CUPS server (which is not there because non-systemd (which is good)).

So is anyone already printing on Obarun, e.g. by using cups-openrc?
You have cups-nosystemd, ghostscript-nosystemd, cups-pdf-nosystemd on the obarun repo. Service are available under the name cups-s6rcserv or cups-s6serv.
Tell me if you have any trouble using it.

So, for the easy way: 
$ sudo pacman -Sy cups-nosystemd cups-s6serv
$ sudo s6opts enable cups
enjoy

note : to see if a package is available on obarun repo just type this on shell : 
$ sudo pacopts origin
obviously pacopts need to be installed first :D.
pacopts compare the package installed with the obarun repo, if you have installed a package with arch repo which is available on repo obarun too, pacopts alert you :)
Eric, your helpful and immediate advice is just the best! Thanks, I'm going to try that (and report back).

EDIT:
Installing cups-nosystemd worked.
Installing cups-s6serv hasn't worked. Pacman says there's an unsolvable package conflict between s6-boot and obarun-runit. It won't let me install it.
Should I activate the Obarun testing repository?

EDIT:
Using the right S6 packages, printing works well now.

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