Each wall of the Obelisk Vase is composed of a voronoi network. However, unlike standard voronois - tessellations that typically form around randomly distributed points - the points here flow in a gradient, from sparse on the top to dense on the bottom. This allows the lower third of the vase to be watertight.
While it's impossible to imagine that this gradient effect has not been exploited before, I've never seen it. After a few years of searching for a piece that makes use of this effect, I decided to make one myself. I'm quite pleased with the result; to me, it's reminiscent of the vines that wind up temples in the rainforest.
Complete project overview here.