Making the snow is not very hard, all you have to do is reproduce what our elders did. During the shooting of the battle of Hoth in Empire strikes back, artists from ILM just used… some salt. A particular salt called bicarbonate of soda characterized by a finer strucrure than the sodium chloride (table salt). The only issue you may encounter is the gluing. The best way I found is to drop of some diluted white glue over the bicarbonate of soda using a big syringe.
Once the structure is made, you have to cover it. For an earthy or muddy ground, the cheaper way is to use sawdust. Of course, you have ta make it but if you use a jigsaw to make the base, you do. First, you must mix the sawdust with diluted white glue. Then, you can apply this mix directly on the primer coat. After drying, you get a crust easy to paint with an airbrush. The last stage is usually a drybrush work on the irregular surface.
Making the ground of a diorama is quite simple. The plaster comes most easily to mind but it’s most often a bad choice. The plaster is easily breakable and doesn’t stick to anything, especially wood. Besides, the plaster dries very quickly, you have less than 5 minutes to work with. I usually prefer to use filling coat. Of course filling coasts are made of plaster but also adhesives and retarders that give time to work. The lunar ground of the Eagle Transporter has been made this way.
Most of the time, the structure is made of recycled wood, you have to learn how to handle woodworking tools. If you need a volume, you can take whatever you find : polystyrene packaging amterial, rubble, polyurethan foam etc. The support rods are generally put in place at this stage to insure their sturdiness. The picture represents the begining of the ‘Battle of Geonosis‘ diorama you can see by clicking on the link.
