Take a weeble, run it through a Minecraft filter, build it almost entirely of open air, and what have you got? It’s called a Bille, and as a monostable tetrahedron – that is, a four-sided shape that ...

The tetrahedron is the simplest of all polyhedra. Any four points in space that are not all on the same plane mark the corners of four triangles. The triangles in turn are the faces of a tetrahedron.