Collision detection in a cup

I modeled a simple cup and I am trying to make a ball fall into it. Problem is that the cup insists on using a bounding sphere for collision detection and the ball won’t go into the cup. Using a convex hull polytope for the cup results in strange behavior.

If the cup doesn’t need to be dynamic, then just change its bounds to static trianglemesh. Convex hull polytope is what the name says, convex. You can’t make concave objects with it.

But if the cup is moving you can’t make it static triangle mesh. You could make the bounds a compound in this case, make the bounds out of a number of convex shapes.