Mix sawdust and flour. Add water, stirring, until dough is stiff. If dough is too crumb-like, add a bit more water and flour (a bit less sawdust)
Knead on a wax paper covered table.
Mold into shape (animals, flowers, bowls, etc).
Set in a warm, breezy spot for about 48 hours until dry.
Sand with fine grit sandpaper.
Paint with acrylic or tempra paints (acrylic coats better, but doesn't come out of clothes)