I get asked all the time how I make my collages. The process is not too complex it is just a little unusual. Here is a security envelope collage video to help illustrate the process.
There is a physical component and a digital component. The computer is mainly used to manipulate the scale of the image. All the colors and patterns are not changed in the computer. Whenever you involve computers, especially nowadays, it can be difficult to distinguish between what is real and what is not.
This video shows the entire physical process of an envelope collage. I am hoping this provides some insight to those familiar with the Snail Mail Security series. Also maybe this will give some artists some ideas on making similar projects. Hope this helps and let me know if you have any questions.