I made my own once....when I was a vegetarian. Basically, you take unroasted, peeled almonds. Soak them in water overnight. Drain them. Put them into a blender add some water and puree it. Then you strain out the solids bits through a few layers of cheesecloth. This is also how you make your own coconut milk and soy milk.
I can't remember what I used it for, but I know I didn't drink it straight.
But I do make a Spanish cold soup called "ajo blanco". Traditionally it's essentially the same recipe as above but you don't strain it and you include in a slice of bread, a couple of blanched garlic cloves, olive oil, a lemon juice or sherry vinegar. I've made it without the bread and it works well (and is Nut Rung friendly!)