Bantam Guineas?

[casuarius]

There already are mini Peafowl. Peafowl are actually a species of Pheasant, so Pheasants are smaller Peafowl in a sense. There are a group of Pheasants called Peacock Pheasants, there are 7 species of them, and they are very beautiful, no larger than Pheasants. It would be very difficult to breed mini Guineas, most breeds of chickens that are miniature or bantams got that way through inbreeding, and holding back smaller or runt birds...which is very rare. Even if a bird stays smaller than it's siblings growing up, most eventually reach full adult size in my experience.