OP, I think you would be totaly justified to drop a hint or two preventively when you see such a facebook post, something like:
"I'm glad you love it! I quite like doing them even if they're quite time consuming, haven't had the time yet to do one for everyone on my list!"
or for the eggs:
"I'm glad you love it! I've been enjoying makind them even if they're quite time consuming, sadly the supplies are getting hard to come by so I'm not sure I can keep up with this craft"
This way people know it's an ever going project that takes time and just because they haven't gotten one yet doesn't mean they'll never get one, no use to fuss (Even if you never planned on getting them one, they don't have to know that).
And as for the eggs, that way they know not to get their hopes up (even if they shouldn't have in the first place) because chances are that was the last one.
Also, do you know if the third party words you are getting were actually said by the envious gift-less? or is it a case of Mary only once saying on FB "Oh they're so lovely, I'd quite like getting one!" in passing (because that's something people say), and Jane comes back to you about Mary being ever so distraught?