In the Spring section you are able to apply spring effect to specific parts of a prop, an accessory of a character or even any part, such as hair, of a character. When the prop, accessory or the character move, the part with spring effect applied will bounce automatically.
After a bone-skinned model or a prop with merged elements is loaded,
click the Edit Spring button in the Spring section and the
Modify panel will switch to Spring Editing mode.
Please refer to the sections below for more information: