Ok I'm going to tell you straight out that it's too much effort.
This involves soaking the soy beans overnight, removing the skins, blitzing them, boiling them for thirty minutes and then straining them. In China we have these soy milk makers where all you have to do is put the soaked soy beans in and then it does all of that otherwise superfluous manual labor and in half an hour you've got your soy milk.
The thing is this does taste very different from your normal storebought soy milk. In China our soy milk is just made with soy beans and water. The soy milk on its own could be more of an acquired taste and I definitely would not put this in my coffee, however, add some sweeteners and/or spices and it's a lot better. Also, fun cooking project. I was going to make tofu but my laziness overcame my ambition.
Makes about 3L
350g dried soy beans
Rinse and drain the soy milk. Put them in a large bowl and cover them well with water - they will double in size so make sure there's plenty of water. Leave to soak overnight
The next day remove the soy bean skins as much as you can. Drain and put in a blender with just a bit of your water (in several batches) and blend well. Put the soy bean mixture in a large stock pot along with the remaining water and bring it to a boil.
Leave to simmer for 30-40 minutes. Strain over a cheese cloth, make sure you squeeze out as much of the liquid as possible.