We start with the PKGBUILD from Manjaro and we will change it to our liking. We need to change the source of the build for example.
https://gitlab.manjaro.org/packages/extra/calamares/blob/master/PKGBUILD
We see what elements we can eliminate. The first thing we see is the _commit.We need to change the url. It should point to this address and more specifically to a download of a tar.gz.
https://github.com/calamares/calamares/releases
We figure out how to change the source url and do not see immediately we are missing one letter : the letter v for the version.
We use the command updpkgsums to update the sha256sums.
We continue to delete elements we do not need. Elements that are specific for Manjaro need to be deleted.We go over the content of our future Calamares installer.
As next challenge we build the next version of Calamares 3.2.18. We only need to change the number.