Two large slabs constructed from varieties of Fischer-Koch minimal surfaces.
The slabs are 3 x 3 x 2 cubes of unit cells, with the central top cell removed to allow placement of a square vase or other similar type of container.
The footprint of each piece is approximately 100mm x 100mm. The square top holes are approximately 30mm x 30mm.
Files are provided plain and with custom supports.
A minimal surface is a surface that is locally area-minimizing, that is, a small piece has the smallest possible area for a surface spanning the boundary of that piece. Soap films are examples of minimal surfaces. Here is a good starting point for learning about some of these surfaces: http://facstaff.susqu.edu/brakke/evolver/examples/periodic/periodic.html
The smaller unit cells used in one of the photos can be found here: https://www.thingiverse.com/thing:4794791
See here for some eggs also made with a selection of minimal surfaces: https://www.thingiverse.com/thing:4789144
See here for surface stl files to make your own: https://www.thingiverse.com/thing:4794791