Make:

Lenticular imagery, the types of photos which change depending on the viewing angle, are really common in children's books and display advertising, but it's also possible to create a simple lenticular image yourself using your own photography. You won't need a zig-zaggy plastic lenticular lens to place over your photo, but you will need a bit of patience, as it requires a bit of photoshop and a lot of folding.

Here's how:

1. open two photos (make sure they have the same dimensions)
2. create a new blank image with the same height and twice the width
3. slice both source images at even intervals and paste the slices into the new image, alternating the image source for each slice
4. print out the new image and precisely fold along the slices to make an accordion

You can tape your new lenticular photo to a firm backing to evenly space each fold of the accordion. The trick is to get all of the angles to be exactly the same. The ideal angle depends on how wide the strips are, how far the viewer will be from the photo, and how far you want the point of view to have to change to see the two images.

If you end up making one, make sure to post it to Flickr and share a link in the comments.