Look on the internet how others make a keyring and look for pkgbuilds.
Personally I have used Manjaro as an example for ArcoLinux. With some common sense you can change it into the package you need.
This time around I would like to use another source. I could have choosen something completely different. Depending if that is indeed a correct code, you will either spend a lot of time fixing it or not.
We use code of others to figure out how to create a package.
Let us change all the names to Carli.
We show you how we adapt the PKGBUILD.
We keep losing carli.gpg file while we build so we keep a copy on the desktop.