Vortex Pool

A swirling pool of water (or lava, or ...), designed to fit into [circle_floor_1-exterior.stl](https://www.thingiverse.com/download:1861483) by [devonjones](https://www.thingiverse.com/devonjones) to form a 4x4 dungeon tile, therefore OpenForge compatible.

The surface detail of the water and vortex should print well at just about any resolution, my test prints have all been at 0.2mm layers.