I'm working on some terain at the moment (however I'm too hung over to do anything today except to suffer - the price for what was hopefully a great party yesterday... this morning). What I do is take mdf board as a base. These are going to be fairly large pieces, so I actually modelled a little terrain (like bumps and puddles of swamp on it. The main feature, however, are dried sticks from my recent garden clean-up. There are going to be huge knocked-down trees on the terrain with a mixture of bushes (from the local pet shop - you just gotta love the plastic underwater plants) but also clumb foilage and the like to have a weird mixture of natural and artificial materials. i always found those pieces looked more exciting to the eye than plain nature ore plain plastic. Maybe I'll post a picture or two when I have something to show.