My colleague Douglas Kelso did a project with the students, where they made drawings in cardboard by scraping away the top layer of paper to reveal the corrugation beneath.
These are really effective, while they were on the wall I began to think of their potential for printmaking. Douglas agreed I could sacrifice his demonstration piece to experiment with and it worked.
Make your cardboard drawing as above, cutting with a scalpel and scraping away the paper surface.
You can then roll it with relief printing ink or even acrylic paint and print.
You get different effects with different densities of cardboard, the direction of the grain and how thorough you are at scraping away the paper layer.
Above: are student prints, from the top: Lee Hutchison, Andy Crichton and below Douglas Kelso's Che