Inverted cube collision hull?

I’ve currently got a set of walls (static meshes) in the shape of a cube, inside of which are floating many objects (zero-gravity), bouncing off the walls and each other. It works great except that every once in a while a small object will get stuck in the corners where the walls meet and somehow clip its way out of the box, never to return.

I’m trying to create some kind of hollow collision box that keeps everything inside of it contained, but so far no luck. I tried a blocking volume but even with BlockAll type collision set, it doesn’t seem to do anything. A cube static mesh with a normal collision hull will not allow things to be inside of the cube.

Anyone have a quick suggestion?

[Edit] Actually to be a bit more clear, the problem most often happens at the corners where the wall static meshes overlap, but sometimes a small object just clips straight through a single wall. It seems unpredictable. I’d mostly just like to reinforce the collision bounds of the box to make sure nothing escapes.

Have you tried to create six separate, aligned walls to create the cube ? Each should have their respective collision geo’s that should work. Just make sure the walls are aligned tightly (use the grid snapping).