More ideas from Vishwanath
The keyboard shortcut to copy all existing layers into a single layer and place it as a new layer on top of the other layers is:PC: Shift Alt Ctrl E.MAC: Shift Option Cmd E.

stamp visible layer = The keyboard shortcut to copy all existing layers into a single layer and place it as a new layer on top of the other layers is:PC: Shift Alt Ctrl E.MAC: Shift Option Cmd E.