For openSUSE Factory run the following as root:
zypper addrepo https://download.opensuse.org/repositories/GNOME:git/openSUSE_Factory/GNOME:git.repo
zypper refresh
zypper install gnome-multi-writer
For 16.0 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/GNOME:git/16.0/GNOME:git.repo
zypper refresh
zypper install gnome-multi-writer
For 15.6 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/GNOME:git/15.6/GNOME:git.repo
zypper refresh
zypper install gnome-multi-writer