https://www.thekitchn.com/how-to-make-almond-milk-at-home-cooking-lessons-from-the-kitchn-189996
QUICK OVERVIEW
How Is Almond Milk Made?
Making almond milk is actually an incredibly old process. We learned about it in culinary school as part of our training in classic French cuisine, but it was made and used long before the French transformed it into delicate blancmanges:
Soak almonds in water overnight or for up to two days — the longer you soak the almonds, the creamier the milk will be. (This is true of any nut milk recipe you make.)
Drain and rinse the beans from their soaking water and grind them with fresh water.
The resulting liquid, drained from the almond meal, is almond milk.