This Photoshop keyboard shortcut will copy all the visible layers and merge them into a new layer. I use this handy shortcut with with nearly every image.
Let’s say I’ve added an adjustment layer to my image plus a burn/dodge layer, clone layer, etc. Now I want to apply a filter to the final result. I could flatten my image, but then I’ve lost the ability to edit those adjustments in the future. An easy way to accomplish this is to create a new layer that is a copy all of the layers and merge them into a new layer.
Select the top layer to make it active, then press Command-Option-Shift-E (Mac) or Ctrl-Alt-Shift-E (PC).
Tip: This will create a merged copy of all the visible layers even if they are above the selection point, so make sure you’ve turned off any layers you don’t want merged!
This can also be handy if you need a merged copy of your textured image to place in a template or frame.