We made the decision to mount light plywood on the wall in most rooms. We found an interesting 18mm thick coniferous plywood. It is nice and light, but heavy.
There was a question of how to attach it. We have a house made of veneer panels, some of the walls are beveled at a slope of just over 60 degrees.
What fasteners to use? Is there any experience of more or less inconspicuous fastening?