Using craft foam to make stamps

I have been working on some activities to do in a creative journaling workshop with high school students.  There are three of us hosting this workshop and one of our goals was to help students get some great effects in there journals with out them having to spend a great deal of money on supplies.  I played around with creating stamps using craft foam sheets.  Easy!  All I did to create this wing set was to draw into the foam with a ball point pen.  It leaves a depression line wherever you draw. I cut out around the outside depression line.  I turned the stamp pad upside down to ink the foam stamp while it was laying on scrap paper.  Then I placed the inked side of the wings down where I wanted them and pressed.  I love the results!  A dollar sheet of craft foam can make a lot of stamps.