First choose your picture, and do the basic editing that you’d like. This is what I’m starting off with:
Step 1: Duplicate layer. Right click on your photo and click ‘Duplicate Layer’
Step 2: Make a new layer Layer>New>Layer
Step 3: Fill that layer with a solid color. Since we’re doing 3D, blue and red would be obvious choices. But you can play around with it the colors if you’d like.
Step 4: Set the blend mode to screen
Step 5: Using the ‘Shift’ Key, select both of your layers,
And then merge them. Layer>Merge Layers or Ctrl + E
Step 6: Set the blend mode of that to Multiply
Step 7: Using your move tool, move the picture to the left or right. Doesn’t matter. And then if you want the red on there too, then you’ll do all these steps again, just choosing a red color instead of blue.
Step 8: I chose to do both red and blue. But of course you don’t have to. That’s just a typical 3D picture. After you’re completely finished right click on one of the layers and click ‘Flatten Image’.
This was my finished product.