You could imagine a glass donut filled with water, as well as a small rotor to move the water in a circle.

You obviously have to balance the water pressure and temperature to reach slow ice formation, and maybe you need a more interesting container shape than a donut to get interesting results.

Well, in space water starts to boil away immediately so you would need a gas tight container which don't typically happen in nature in sizes that would allow internal currents to develop.

Earth is a (reasonably) gas tight container filled with flowing liquid (lava propelled by convection currents). Europa (the moon) is a reasonably gas-tight container filled with water under an ice sheet.

Of course Earth also has appreciable gravity. The real problem isn't that nature produces no gas tight liquid-filled containers, it's that gravity is the primary mechanism by which things are naturally created in space. Asking for a situation without gravity virtually requires artificial construction.

I wonder if water ice in space forms large geometric patterns if it is sufficiently dense.