I designed these using a online Lithophane generator then using Fusion 360 to make some small changes. The print profile includes both plates for AMS and swapping filament during a pause. You could probably get better results on some of the covers if you took the time to paint in some different colors in certain areas, but it still turned out really well without. After printing, I modified the Dark Age STL to flatten out the surface and give it a thickness uniform with the rest of the covers, so it should look better than the photos when you print it.
If you have any questions feel free to ask!
Filament used:
OtterBox PLA White
Bambu Lab PLA-CF Burgundy & Black
Bambu Lab PLA Silk Gold
Bambu Lab PLA Tough Blue
OVV3D Silk PLA Red-Gold
(Printed on an enclosed P1P without AMS)