Just in case you're interested, here's my small amount of accumulated wisdom on the topic of Coconut Milk:
Ingredient: 4 mature (brown) coconuts.
Time: I have not been able to complete this process in under two hours...yet.
Equipment: Hammer, awl/butter knife, potato peeler, nut milk bag, Vitamix or similar blender.
This makes about three quarts of milk, or two quarts of cream plus one quart of fermented coconut water.
First: use a hammer and a butter knife/awl to poke two holes in the top of the coconut, right where the coconut has natural dents. Let the water drain out, and taste it. If it's good, save it. If it tastes funny, toss it out, and be wary that at least some of the coconut meat inside may have mold (you can still use the part that isn't moldy, but you MUST be careful not to include the moldy bits, because they taste gross).
(Alternatively: as of March 2013, I have discovered a slightly easier (though not easy) way to crack open a coconut: freeze them for 24 hours, and then whack with a hammer as described below. The water inside will have frozen, and is fairly easy to remove after opening the coconut, and once it's slightly thawed the meat is easier to remove from the shell than if you haven't frozen it first.)
After you drain the water, take the coconuts outside (into the snowy frozen tundra--just like they do in the tropics!), and bring the hammer and some gloves and a big bowl. Smash the coconuts all around the equator, and then further smash them into manageable chunks (like 4-6 inches across). The gloves help avoid injury in case of the hammer breaking a shell-crack that might catch your finger and then snap closed and hurt a lot.
Now, go back inside and thaw out yourself and your coconuts. What follows is at least a half an hour of work that requires a butter knife and a lot of patience, while you pick the meat out from the thick outer shell. (If it's moldy, it will look a bit greenish under the thinner, inner shell.) I've tried it both ways, but I think that you get more cream out of the coconut if you also remove the thin brown inner shell. I use a potato peeler for this. And sometimes I do not worry about removing it at all.
Wash all the chunks to get off the dirt and coconut coir stuff that is probably all over them by now.
Now, put the chunks of coconut into the Vitamix along with the coconut water and additional water to cover, as needed (two or three batches will be necessary if you use four coconuts). It is easier to blend with more water; the resulting coconut milk is also less flavorful this way. You gotta kinda do what works for you and your blender.
Okay, so now you have a slushy, pulpy mess in the Vitamix. Keep blending, and pushing the pulp down with the plastic plunger, until the mixture is noticeably _warm_. This warmth makes it MUCH easier to get all the cream out of the pulp.
You'll need to press the pulp through a nutmilk bag. I've tried to fill the thing completely with ALL the pulp/milk, but now I've realized that it's really much better to do six or eight tiny batches, so I could really wring/twist/press out all the milk.
Oh, and then yes: if you're not up for drinking sweet, creamy goodness as-is, let it ferment overnight! I use water kefir grains, about a tbsp. in a gallon jar, filled about halfway or a little more with the milk. Overnight, the cream rises to the top and then separates out further into bubbly layers and everything now tastes tangy when it's done. You can stir it back in, to make milk, or store the cream and coconut water separately.
And oh....it makes me want to fly somewhere where I can eat this all the time!! :)