Hi...Paper towels work just as well, and are a sight cheaper. You'll need regular plaster and heavy duty paper towels (the brown type)....You can find both at the local hardware store. Check the plaster's mixing instructions..Normally it's two parts plaster to one part water. For dipping towels I use just a bit more plaster than water-a nice soupy mix. Cut the paper towels in half (easier to handle)and dip them in the plaster mixture, let the excess run off and place over whatever you've used for landforms. Don't try to do a lot at one time...slow and steady is better. After the plaster has dried you should apply at least one more (2 is better) hands of plaster.
Here's some pics of a "mountain range" I'm working on. It's all paper towels w/plaster over a cardboard strip/masking tape framework.
Good luck..!!