“Bille” is the first-ever monostable tetrahedron, or a pyramid-like shape with four triangular faces that has one stable ...

This KS2 maths article explains how to find out what a net is and how they can be used to build 3D shapes.

There are many types of nets for the different 3D shapes. A net is made from polygons that can be folded and joined to make a polyhedron. Here is the net of a triangular prism.