Here I am, late to the party.
I made mine from some weird 4-ply cotton I had that is slightly thicker than embroidery floss. I used a size 1 steel hook, and it came out to about 5 inches. (The coin in the pic is a quarter for size.)
Please excuse the lack of blocking...I'm going to do them all once they're done, try to get them to match.
I don't know what the heck I'm going to do with the squares at this size, though. Scarf, maybe? Any thoughts?
On a slightly unrelated matter, how do you all get your pictures of your work to look so nice? This was the best I could manage, and it still looks kind of overexposed or something.