Example below:
The wires need to run up behind the wall to the ceiling (see image below). A return was created between two existing walls (you will need to create two columns) - through which you can run the wires if necessary. The screen is hidden in the beam above the painting.

In the foreground of the photo is another "beam" which actually contains the projector. It has an access panel again covered in the mesh and there is a flap that can be removed or opened/closed when the projector is in use.

US is way more advanced, so I believe other Houzzers can step in...

Thsnks. . The panel seems to be a great idea to hide projector