A small box holding a complete world with water simulation.
3D Artist Ryan Will presented a very lovely animated diorama of Char Aznable's Zaku, or what seems to be Mobile Suit Gundam: The Origin's MS-06S Char's Zaku II specifically, placed in a Pacific Rim-like environment with smooth liquid simulation made with FLIP Fluids Blender add-on.
In the past, Ryan Will has also recreated Char's Hyaku Shiki and Sazabi in 3D:
There's plenty of other Gundam fan art on the artist's page, including Haman Karn's Qubeley, Shiro Amada's RX-79, Z'Gok hangar diorama, and more, so check it out here.