Place almonds in a bowl and pour in enough water to cover; soak at least 12 hours. Drain water.
Blend almonds and 3 cups water in a blender on low speed for 10 seconds. Turn blender off for 5 seconds. Blend almonds and water on high speed for 60 seconds. Pour mixture through cheesecloth or a nut bag into a bowl. Discard the pulp or save for another use.
Clean the blender and return milk to blender; add agave nectar and salt. Blend milk until smooth.
