*** What are you attempting to achieve?**
create a box with a hollow and union.
*What is the issue?
can’t work properly, we can’t work in it well the parts try to get outside…
*What solutions have you tried so far?
I have changer the Collision Fidellity to precise convexdecomposition and i tried with 4 wall union and 1 part and 1 negative part union
( That is my first DevForum post 
)