Tri-lobed element interlocks with it's neighbors to form a flexible surface.
You'll need great cooling to print this and fine layers, I recommend layers 1/6'th of your nozzle thickness and there's some bridging so put the actual nozzle diameter into your slicing software for this print.

Or you can order a stronger one in nylon which I've posted here:
https://www.shapeways.com/product/629RP6H26/flex-lattice-coaster