Spins by Kilz has been producing Manjaro spins since 18.1.2. Each spin has had a unique theme consisting of Wallpaper, Kvantum, Gtk and for the most part greeter and grub themes.
The themes are usable on most desktops except KDE, its theming is quite different.
The themes are available in the signed SbK repository that can be added to any Manjaro/Arch system.
Click here to check out the full themes and which packages are needed to use any of the 51 themes.
As always comments, suggestions, requests are always welcome, just post below.