You're talking about this part ? Well, yes, I think this would perfectly fit with this part and XT4's body, to make little MOCs, like chibi creatures. But I don't know how to do such a part, I don't even think it's possible, since the balljoint side requires about two studs, and the socket side too. I think this part would be very fragile if it was made for real. But... thank you !
Also, I would like to see more purple parts (especially hands and feet), and hands in gold, gunmetal, purple... There is too much black and silver, we need more ! Oh, and more medium azure parts.