How to make Mystery Box Animation?

I need guidance on making a mystery box show a little animation of which animation you get like in Murder Mystery 2. It just doesn't make sense how they do it.

First get a plugin that allows you to create custom humanoid parts. I recommend you use this plugin: https://www.roblox.com/library/171922549/Character-Creator-BETA Once downloaded make a chest. Now open the plugin and make 1 part connecting the top opening part to the main part. Now get a animation plugin. Click on the chest and click the part you made. Now you can move the rig part up and down and you're done.