Here is an "alien world" set up I am doing for quick and dirty science fiction games in 3mm. I wanted something cheap and cheerfull and simple. Hills are "wedding cake" style with dunes sloped on one side. They are both made out of foam core, covered with artist's PVC gesso.
The boards themselves are just MDF slabs covered in gessoed canvas, bought at my local art supply store. The forests are bits of loofa sponge, flocked with various colors. The Alien Idol is some kid's cereal prize I found on the street and re-purposed.