Nut Milk Bag
Nut milk is simple to make, and making your own is much cheaper than buying a pasteurized pre-made nut milk.
Just blend the ingredients for your nut milk (can be as simple as water, nuts of your choice and an optional sweetener), then strain through the nut bag. The tighter weave ensures that no pulp will end up in your milk.
You can also use a nut milk bag for straining more juice out of pulp.