Detail this asset from Unity Store: Original Link
This is a paid asset, but now you can download Compound Collider Generator Free.
Compound Collider Generator v1.1
This content is password-protected. Please verify with comment to show the download link. Thanks.
Concave colliders made easy!
Compound Collider Generator (CCG) is a tool that makes creation of collider meshes for complex, concave shapes easier. Using the Unity feature of Compound Colliders, CCG automatically creates child objects with Collider components on your selected GameObject.
Compound colliders allow you to create concave collision meshes for your dynamic Rigidbody objects, a feature not possible when using concave MeshColliders. Compound colliders also typically give better performance than MeshCollider objects and better reliability.
Currently CCG can create compound collider shapes for:
• Rings
• Bowls / Bubbles
• Barrels
• Open Boxes
For additional information on Unity’s Compound Colliders feature, see the official Unity Manual page