In large bowl pour hot water over the margarine. Stir in powdered milk, salt, and egg. Add flour, 1/2 cup at a time. Knead for a few minutes to form stiff dough. Pat or roll to 1/2 inch thickness. Cut into bone shapes. Bake at 325 degrees for 50 minutes. Cool. They will dry out quite hard. Makes about 1 1/4 pounds of biscuits. Costs around 30 cents per pound.
Variation: increase margarine to 1/2 cup and add 2 teaspoons sugar.