I use blanched almonds, either whole or slivered. The skins contain tannic acid and are a stomach irritant. Or I blanch them myself, by dipping in boiling water for about 15 seconds, then peeling off the skins (while they are still moist). Then there are 2 ways to go.
Method 1
The first method is to grind the blanched almonds into almond butter, then put some of the almond butter into a blender and blend for just a minute or so. You can make almond milk, or with less water, you have almond cream. By adding water to almond cream, you have almond milk. An advantage of this first method is that almond butter keeps a long time; almond cream and almond milk need refrigeration, and even then, they keep for only a few days under refrigeration.
Almonds blanched recently in hot water must be dried first for many hours before you try to make them into almond butter. If the moisture level of the almonds is too high, it will be very difficult or impossible to grind them into butter.You'll be grinding and grinding, and they won't be butter yet. You can grind nuts into butter in many food processors (without using water). Follow the directions that came with your food processor for grinding nuts into nut butter. Or if you are fortunate to have an appropriate mill, you can grind them in a mill. A mill that can grind nuts into butter (as opposed to nut flour) can be very expensive. And you may have to run the nuts through more than once. No matter how you grind, food processor, mill with stone burr, or mill with steel burr, make sure the almonds doesn't get much hotter than body temperature. Or you might be able to find a company that will mill them for you. Make sure they know you want the almonds milled into nut butter, as opposed to being milled into nut flour.
Method 2
The second way to go is to put water and whole or slivered blanched almonds into a blender, and blend for about 3 to 4 minutes at highest speed. With this method, you don't make the almonds into almond butter first. It is that simple. I often make it rather thick, as thick as the blender will do without sounding unduly stressed — I'd call this product almond cream actually, not almond milk — using perhaps 30-40 almonds per cup of water. Then I water down the almond cream when I need almond milk. But you can also use the blender to make the product the consistency of milk.
For some unexplained reason, some people don't like finding an occasional little almond particle in their almond milk, but I find no need to filter the nut milk in any manner.
In the United States I cannot get almond butter made from blanched almonds so I must make my own almond butter. However I've gotten blanched almond butter from a friend in Germany.