1.-I started by collecting dirt from the yard. It's better if you can get the dirt from a stream bank or a washed-out area, where no grass is growing.
That way, you don't have to deal with a lot of grassroots. You'll need at least an ice cream container of dirt.
Be sure that the dirt is completely dry. Otherwise, the dirt will not grind down, but instead just clog your sandpaper. You can spread it out on several sheets of newspaper overnight to dry it out.
You will also need some containers, a spoon, some 60 grit sandpaper and a block of wood to wrap the sandpaper in.
2.-Sprinkle about a 1/4 cup of dirt onto a sheet of sandpaper.
Then take a strip from a separate sheet of sandpaper and wrap it around the block of wood. If you don't have a block of wood, anything hard and flat will work.
3.-Using a circular motion, grind the dirt until it's about the texture of ground coffee.
While you're doing this, remove any rocks or roots that you may run into. Either throw them away or save them for where you need larger ground cover for your model.
4.-Pour the ground dirt into a container. It will be sifted later.
When your sandpaper clogs up, use a stiff bristled brush to clean it off. Then pour this fine dirt into your "fine dirt" container.
If the sandpaper does not want to clean this way, then your dirt is still too wet.
5.-To sift the dirt, tilt the container and lightly tap the bottom. The fine dirt will settle to the bottom, and the coarse dirt will come to the top. Scoop this coarse dirt out using a spoon.
Now stir the dirt around with a spoon. Tilt the container and lightly tap it. Scoop out the coarse dirt and place it in the "coarse dirt" container.
After you have repeated this process about six times, the dirt will be sifted pretty well, and you will have a container of "fine dirt" and a container of "coarse dirt". Click on the photo for a larger view.
6.-When you're finally finished, you'll have two containers of dirt. One will contain fine dirt the consistency of flour. The other will contain coarse dirt, the consistency of coffee grounds.
7.-The dirt will need to be sealed using cheap hair spray (not your sister's or wife's) and will set up to be very durable once it's dry and finished.