Blend in butter until mixture is mealy.
Add enough milk to make a stiff dough and roll out very thin 1/4-1/8" on a floured surface. Cut into shapes with a cookie cutter. Make holes with a fork or a tine tool. Brush tops with milk and lightly salt.
Place on a slightly greased cookie sheet. Bake at 400 for 15-20 minutes. This will yield several dozen crackers.