Cut the border by eye. The criss-cross lines also by eye. Perhaps a few quick layout lines were put down with a pencil right on the steel to keep things straight,,but I really doubt it.
Just a V shaped point, nothing fancy.
The very fine work in the center of the mount is done with a multi cut 'liner' tool. A series of cuts at 90degrees to each other. Same type used to do the background to the bold criss cross cuts on the other surfaces only this time just cut in one direction.
If the whole thing took the person 5 minutes, I'd be surprised.
