Jigglebones

This is an addon that adds jigglebones to Godot 3.0. If you don’t know what that is: jigglebones are bones that jiggle when the skeleton moves. They are used for procedural animation, so you can move only the important parts of the skeleton and the little bits will automatically jiggle with it. You can also drag the jigglebones in the editor and fiddle around with them.

See the GitHub page for a detailed guide on how to use it in your project:
https://github.com/Bauxitedev/godot-jigglebones/blob/master/README.md