Photoshop Tip : Create a flattened layer AND keep all your layers intact in one file
When you’re working on a project, whether it’s photo retouching, graphic design or web design, it’s always a good idea to carefully keep an original PSD file with all your layers intact. Then if you want to come back to your file at a later time, you still have all your layers to play around with. When your work is finished you can send a flattened version to your client, or put it on your website portfolio. So now you have two files, your layered PSD and your flattened (and usually much lower file sized) single layered file.
But what happens if you want to have BOTH of these in one file. Is that possible? Why yes, with the power of Photoshop, it is indeed!
If you want to flatten an image in Photoshop, you don’t need to make a duplicate file in order to create a fattened layer while keeping your original layers. You can use this keyboard shortcut to have both in one file.
In windows, use Ctrl + Alt + Shift + E
On the mac, use Cmd + Option + Shift + E
In the example below, you can see the layers panels on the left has four separate layers. By using the keyboard shortcut above, Photoshop creates a new layer for you and places a flattened version of the image into this layer. This is such a handy option, and I use it all the time with my work in both illustration and design.