The TRIZ Nested Doll principle is based on the Russian Matryoshka dolls, also known as nesting dolls. These dolls are traditionally made of wood, and they are carved so that one doll fits inside another. The largest doll is hollow, and it contains smaller dolls, which in turn contain even smaller dolls. In this way, a single object can contain many smaller objects. This principle can be applied to any situation where one object needs to pass through another, or where multiple objects need to be contained within a single object. For example, if you need to get a large number of small objects through a narrow opening, you can place them all inside a larger container. This will make the task much easier and will prevent the smaller objects from getting lost or damaged. The TRIZ Nested Doll principle can be used in any situation where space is limited or where multiple objects need to be contained within a single object.