A Quick Tutorial
Multiplicity is a pretty straightforward process. I would recommend that the photos are taken with the camera mounted on a tripod, and if you are going to be in the photo multiple times use the timer function. (I used a remote trigger with a delay of six seconds.)
First load the five photos to be used into Photoshop. Select two (to start with) and switch the view so that they are side-by side:
Press Ctrl a to select the photo from one window and use the move tool to move the selected photo into the same window as the other lining them both up.
There will now be two layers: “Background” and “Layer 1”
Use the eraser tool and rub over the photo at the point that the item you want added to show through (from below) the photo you can see.
When you are finished adding to the photo (Right click the layer and) merge them together.
Once the photo is flattened then crop/straighten and make any aesthetic adjustments desired.
Have a little fun with it!!