A császár polyhedron is a 3D shape made up of lots of flat surfaces, called faces. Imagine a big ball made out of smaller balls stuck together in a pattern, like building blocks.
A császár polyhedron is special because it has a really neat pattern that repeats itself over and over again. You can imagine this pattern like the tiles on the floor or the design on your shirt.
The császár polyhedron has 14 faces, which are all the same shape and size. These faces are shaped a bit like a slice of pizza with curved edges. If you put all these pieces together in just the right way, they form a perfectly symmetrical 3D shape.
The shape is named after a mathematician called László Fejes Tóth, who studied how these shapes fit together. It's really hard work to figure out how to make a császár polyhedron, but it's also really fun and rewarding.
In summary, a császár polyhedron is a cool 3D shape made up of many identical pieces, arranged in a special way so that they form a repeating pattern.