Body from inside?

Hey this might be a kind of weird questions because i am not sure if i am asking it correctly. But is it possible to us a large body, but instead of colliding with the outside of the body, have something inside it? I guess so if there was a sphere for a round room, could you just create a static sphere body, and place the characters inside the sphere?

You would have to have like a hollow sphere I think.

Yeah, i guess. It would just be a room in the shape of a sphere. And am wondering how to handle collisions? Like would it be possible to just create a sphere body that fits the walls of the room?

If you make it in max, for example, I'd probably make a trimesh out of it.

Triangle mesh is the only way to do it, using any other shape is quite difficult to do.

Okay, thanks i'll do that.