Smart Object Instead Of Stamp Visible
For years I’ve been telling people to press Command-Option-Shift-E (PC: Ctrl-Alt-Shift-E) to make a merged copy of all visible layers. The only problem with that method is it’s a snapshot, so if you change the underlying layers, the merged version will not change. Instead, select all the layers and convert them to a smart object (Layer>Smart Objects>Convert to Smart Object). Now you can work on that layer, but still have live access to all the original layers just by double-clicking on the smart object.
by Dave Cross