how i can make only one static object has collision like bucket or cavity

how i can make only one static object like a Bucket that for collect balls and when I rotate it I want Balls are falling from it … i I tried that but the exact problem is static object collision do not … so how I can make only one static object has collision like bucket or cavity?

You can’t have a concave collision mask for an object, so instead make the bucket object out of 3 parts (the two sides and the bottom) and add physics behaviour to each. Place them on the scene so the two sides overlap the bottom, and in the code add weld joints between each side object and the bottom object

Well, I did earlier as in your answer, but this is not a solution for linked static objects. Because every object will rotate in the opposite direction of the linked objects… this will disrupt the work of the one hollow object. I also tried to set the center points of the objects to one place to rotate like one object… but the collision mask will be different with changing the center point and not attached to the shape of the object.

I forgot to ask - why are you making your bucket a static object? Static objects are meant to be just that; static - i.e. not moving and do not respond to forces. You shouldn’t use a static object for something that moves.

Dynamic objects will respond to joints and forces. Use the dynamic physics object type for your bucket.

because I can’t control dynamic objects… for example how i can Rotate the bucket to empty the balls out of it if the bucket is dynamic?