Homemade natto?

I was wondering if anyone's ever made their own natto? How easy is it? I actually haven't tried natto yet, but I do have dried soybeans on hand. I know I'd probably have to scrounge around for the active ingredients, which might be even harder to find than prepared natto... but I'm scared of buying something only to have to throw it away; at least if I made it myself, I could make a very small batch, and disguise it.
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