Trigger a Door Opening

Dear Maratis enthusiasts,

I have created a door in a wall separating to another room.  It has two entities: 1.  the room/wall, and 2. a door. 

The door has been created to pivot on the end, like any normal door.

Problem:  How should the door open??  I thought it might be best to use a trigger (box)?, like the earlier trigger sound experiment. 

https://www.dropbox.com/s/cbwrvzvbqaw00 … R.jpg?dl=0

Other suggestions are welcome.

I herein enclose a link to the 7z experimental Project file:

https://www.dropbox.com/s/8o9r3q690ajca … OR.7z?dl=0

Play around and do share your ideas.

many kind thanks for time.