Keep objects in an interactable, grabbable box

Hi,
in my project, you can put items into a box, and than grab the box and move with it.
The problem is the items in the box are jittering, and often falls out from it, even through the walls ignoring the colliders. When an item putted into the box, the box is set to its parent. It works with one or two item, but the more the object, the more it falls out.

Is there any good solution for keep items inside the box?

Sorry for my bad english.

 

Hi,
Did you try to adjust your projects Physics settings? I dont' see you mentioning that, so it would probably be the first thing to check. Try to adjust Default Solver Iterations and other settings and see what happens?

 

Unfortunately, Default Solver Iterations did not bring the desired effect, but your post gave some good ideas that brings acceptable results. Some playing with the rigid bodies masses, increasing the Default Contact Offset, and turn on the Auto Sync Transform seems solve my problem. (I have not yet examined how this will affect to the rest of the project.)
Thank you for your advice.