An example is better than words.

First thanks to shironeko to contribute.
You can find its own OUR here

Do you want emacs without systemd already built for you?
Just download the package here.

Extracts the zip archive somewhere and install it by pacman -U.

You want to see the build logs of the emacs package?
see here

You want to retrieve the PKGBUILD for a previous version?
see here

So, everyone can maintain its own package and share its binary easily with other user.
Furthermore, The package is build on the same environment than any official Obarun packages.

You want to be notificied when the package change?
Just use the notification feature of the gitlab instance

Please, read the wiki page (first post) and ask if you get stuck.

Basically, you can get any PKGBUILD that you want and replace the one found at the trunk/ directory of you OUR project. When you commit a change at the PKGBUILD file the build is made automatically, just wait and download the binary.

Can you add/search obarun through pacman or does it need an our-helper

Not for the moment, the final goal is to provide a way to be able to append your pacman.conf with e.g

[shironeko]
Server = https://repo.obarun.org/our/shironeko

But it will take time to reach this target.

How would this work, can one repository as our show all sub-repositories, or does each need a specific entry

subgroups should be avoid like our/shironeko/<subgroups>/project. The our/shironeko/ should only contain project not subgroups.

To be read by pacman it needs a db file indexing the pkgs listed and a sig file if the packages are signed by gnupg keys.

This is not the purpose of the gitlab instance. The most difficult part is to move the result of the build to an ftp server and provide the correct pacman db added with the fresh package built.