Knitted Hats

Knitting hats is pretty much instant gratification.  If you make a mitten, you have to make another.  If you make a sock, same thing.  A bored knitter, or for that matter an adventurous one,  can create mismatched pairs.  Still, such things must happen in twos.  But not hats.
It also helps, paraphrasing Elizabeth Zimmermann, that people [...]