making "mud" for figures, tanks, and autos...

There's a good tip for making mud from ground pepper in the armor forum. Might want to stick your head in over there and take a look around.

You can also use Celluclay to make thick, caked-on mud.

Of course, there's nothing better than the real thing: Take some dirt from your yard and sift it through an old piece of window screen. Mix it with a little water and white glue, then take a brush and apply it until you get the effect you want. For splatter, take and old toothbrush and dip it in the mix. Take your fingers and bend the bristles back, and then let them go....
Make sure you practice a bit so you can direct spatter in the direction and concentration you desire.

Gip Winecoff

Everybody has their favorite snow product. Here are a few I can think of; powdered alum, baking soda or baking powder for light snow, Plaster of Paris (wet) for heavy drifts. Hudson & Allen Studio, Woodland Scenics, Vintage Reproductions and many other companies make snow products. Some have iridescent crystals added to make the snow sparkle. They also make slush and ice products too. Check out your LHS or model railroad shop or search online for these products. Most are applied by simply undercoating with white glue and sprinkling the stuff on. Stay away from flour, corn starch or baking powder that contains corn starch, as these will eventually decay into a sticky mess and turn your diorama into a Uncle Milty's House Louse Farm.

thx for the help. I'll try both ideas. Also, how would I make snow in a diorama? Pardon all the questions; I just don't have the resources to try things and have them fail on me.

I have used regular testors contour putty and mixed with brown paint with some small brush bristols mixed in. Then just took an old paint brush and slopped it on. Looked pretty good.

You can mix brown acrylic paint with talcum powder or spackle paste. This works well. Stir in some static grass, sand or sawdust if you want it "chunky" style. Dry brush with light-brown, tans or khaki when dry, then wash with dark brown-black to add some depth and shadow. I also use acrylic gel medium, available at art supply stores. It comes in several different viscosities and either gloss or matt finish. Mix with paint and goodies as above.