Let's Tesselate!

thingiverse

These small sand molds let you create intricate beach designs using tessellations. Invented by Roger Penrose, the kite and dart patterns allow for aperiodic plane coverage. You can learn more about these mathematical tiles at mathworld.wolfram.com/PenroseTiles.html. Rep-tiles are shapes that can be combined to form larger versions of themselves, making them ideal for beach art since they can always be scaled up exponentially. A fish-shaped Rep-tile would be a great addition to the sand, and you'll find more information on tessellations at overlordoftheuberferal.wordpress.com/tag/tessellation. The molds come equipped with air holes that help prevent suction when demolding, a problem that has long plagued sandcastle builders. The air holes are strategically placed so you can cover them with a finger while filling the mold, even if wet sand is unlikely to fall through anyway.