Collagraphs are printed collages. I have a sack of materials - hessian, cardboard, crumpled paper, silver posterboard, discarded plastic items, twine, &tc. - that become part of my collagraph plates. I start by sketching the outlines, and then go crazy snipping, ripping, and pasting things to the plate. Finish with a few coats of clear polyurethane and ink it up!