A doll box is a clown with springs in a wooden box. As soon as the lid was opened, the clown would jump out, which was very popular in Europe at that time.

The principle of the doll box is that when the lid is closed, the lid gives a resistance to the spring, which compresses the spring connected to the clown. Then open the lid, the spring has no resistance, so it pops out and pulls. In fact, all the mechanisms are on the spring.