All you need is a bowl, a strainer, and some elbow grease. First, soak the oats in water for at least 30 minutes. Then, drain the oats and rinse them well. Put the oats in the bowl and add enough water to cover them. Use your hands to mash the oats into a pulp. Once they're sufficiently mashed, put the pulp in the strainer and press it with your hands to extract as much liquid as possible. The resulting oat milk will be slightly thinner than store-bought oat milk, but it will still be delicious and nutritious.