re: Source for small black oxide wood screws?

Did you check D Lawless?  I bought some nice small screws from them for my hexagonal bin about 9 years ago.  I think that they were #5 pyramid screws but they have some round #2x1/2.  Not slotted but they do have #2.  Note that a #5 is only 1/32" bigger so you might be able to simply enlarge the holes if you want the pyramids.   The screws are cheap but as I recall, the shipping is not free so you might want to stock up on various sizes of small screws while you are at it.