How to make fake rock walls?

I'm making a fake bat cave in my basement in a 10' x 12' room. I've stapled chicken wire around all the walls of the room and bent it to have the ups and downs of a cave wall. My plan was to use plaster of Paris and cheesecloth to panel the chicken wire, but it doesn't stick to the wire on the walls. I'm not sure what else to do -- I'm not even sure paper mache will stick. I need SOMETHING to stick to the shaped chicken wire. But how?