While I was at Art and Soul in Virginia Beach, I was lucky enough to take a photography class taught by Catherine Anderson. The first part was based on an activity in her book, The Creative Photographer (I REALLY recommend this book, which is full of exercises and information about taking and digitally editing photographs). We brought our own photos of doors (or, in my case, windows) and images to put behind the doors (Catherine provided photos in class, for people who didn't bring any).
We backed the door/window image and then cut open the door or window. We then put an image behind it. To give it added dimension, we placed the background image on a 5x7 canvas board and used black foamboard around the edges to lift the portal image.
Many people added words to the images and I may do that later, to personize them for the people I will give them to.
Here is my photo of a window in Alexandria, Egypt.

Here is the window open, revealing a photo of a tree at sunset (I took the photo in South Africa; I liked the idea of using images from the most north and south points of Africa).

This is a photo of a window in Jerusalem. It's partially open because it didn't stay very closed with the way I cut it.

Below is the Jerusalem window open, revealing a mermaid and her baby (I thought there was a kind of magical quality to the window, so I wanted it to open onto a fantasy image).

Below is a photo of the Cathedral in Sienna, Italy. I love that a piece of the countryside is reflected in this window.

Here is the window, opened to reveal a stone angel (I took the picture of the statue in a cemetery in Houston, TX) in the Heavens (can't remember where I was when took the cloud photo). There's a little piece of paper that matches the backing of the window (frankly, it's there because the photo wasn't quite long enough to fit behind the open window).

The last image is of some Stained Glass Windows at the National Cathedral in Washington DC.

I put the laughing Buddha (the background is a poppy from my garden) behind the Cathedral windows because I thought the color and spiritual image fit.

We made our photo pieces in the morning part of the class. In the afternoon, Catherine sent us out to take photos. We were reminded to take close ups and to take photos from more than one angle. It was a great exercise.
As you can, no doubt, tell, I loved this class.