This is a tutorial on how I carve and paint extruded polystyrene (XPS) to make cheap fake rocks for a model scene or diorama. These techniques can be used for model railways (N scale, HO scale, on30 and more) and also look great for gaming terrain such as wargaming tiles and boards. The final shots have some static grass added for extra realism. Foam rocks have an advantage over plaster moulded rocks because they are super lightweight ensuring your board or diorama doesn’t become too heavy. The technique is also cheap and only requires basic paints and tools.