We've included some sample terrain generators over the following pages, but it's easy enough to come up with your own customised one which includes all the terrain in your own collection. The terrain generators we've provided are really intended to be a source of inspiration – the galaxy is full of all kinds of different worlds and the following terrain generators are just a small sample of what you could do.
Random terrain generators aren't just useful for setting up games. Some gamers use them as a rough guide to focus their terrain collection, building up model forests of ice crystals, crevasses and glaciers to make up battlefields on an ice world, for example.
On the other hand, you might decide to make the terrain generator fit the collection you already have. Simply write down all the pieces of terrain you have, assign numbers to them and you have your own customised terrain generator!
Four sample generators are given, one each for an Ash Wastes, Agri-World, Ice World and Death World. See also Different Worlds for further inspiration on other kinds of world you could model.