1001 Surprises Eggs

Kinder Surprise, also known as a Kinder Egg or, in the original Italian, Kinder Sorpresa, is a confection manufactured by Italian company Ferrero. Originally intended for children, it has the form of a chocolate egg containing a small toy, often requiring assembly. "Kinder" is the German word for "children".

Each Kinder Surprise egg consists of a chocolate shell, a plastic capsule, the contents of said capsule, and an external foil wrap.

http://youtu.be/v1OeFcpgkGQ
The chocolate shell is shaped like a chicken's egg, and is of similar size. It is only about a millimeter thick, and consists of two layers: a milk chocolate layer on the outside, and a white chocolate layer on the inside. The shell is not a singular piece of material, but rather two identical halves split down a vertical line. These are lightly fused together just before the egg is wrapped, to prevent the halves from splitting apart under the light pressures expected during transportation.

During the egg's production, before the halves are fused together, the plastic capsule containing the toy is placed inside. This capsule is made from thin, flexible plastic, and is often yolk-yellow (though in the past it was also manufactured in a variety of colors). The capsule is made of two non-symmetrical, overlapping pieces: its bottom piece is almost as long as the entire capsule, and has two ridges protruding along its outer rim; the top piece is about half as long as the entire capsule, and has two corresponding ridges along its inner rim. When the pieces are pushed together, the ridges interlock and do not come apart without manual manipulation. To separate the two pieces, it is often necessary to apply pressure to the interlocking region at its opposite ends, bending it and causing the ridges to separate inside so that the halves can be pulled apart. Once the capsule is opened it can be re-closed effortlessly by pushing the two pieces back together.

https://www.youtube.com/watch?v=v1OeFcpgkGQ