This paper has an unusual coating that swells up when heat is applied. It's normally used by printing on it with a standard inkjet or laser printer, then exposing it to a very bright light. The dark areas absorb more energy, and become raised. I also experiment with the material in a laser cutter.
http://www.americanthermoform.com/ - Source of the paper used in this video
https://www.youtube.com/watch?v=0fIg4rI4cDw - Video about the U Michigan group