I've been revisiting some of my photography projects during lockdown and came across an experiment in which I had combined two photos into one. As you move past the image, you see one picture and then the other. I've just filmed a very short video about the project.
This was how I created the 'lenticular' image: Using Photoshop, or equivalent, slice each picture into ten equally-sized vertical strips. Then create a canvas double the width of each of the pictures and paste in the strips alternately. Finally, fold along the vertical lines between the strips, with valley and hill folds alternately. The two images in the demo were taken in St Peter's Square, Rome, in late evening, in June 2017.