So, the Merinita Mystery Animae Magic can transform items into faeries and even summon faeries out of nothing (I guess they are summoned from somewhere, right, or are they made from nothing?).
So, would it be possible to make an item into a faerie permanently as a magic item? How would this work? Would it work, somehow? Could these new guidelines be invested into an item? 
E.
It's up to you to decide where they really come from. The book says they're summoned.
Looks like it. Other people think so too.
Yup. Personal range, Sun duration, +4 for constant effect. You'll certainly want to use Muto on the physical form of the device you're enchanting, rather than Creo.
You can thus create something like:
Electrum Necklace of the Stone Guardian
MuTe 30
Created as charged items, each pendant can be laid on a boulder of size up to +3, which animates into a faerie wearing the pendant (Might 1). Removing the pendant permanently destroys the faerie.
Base 5, +1 Touch, +2 Sun, +1 Size, +4 levels Constant, 1 levels Might
(Electrum has a MuTe form bonus)
Or
Ritual the Phoenix's Rebirth (ok, it's not technically a ritual)
MuIg 49
Enchants a bonfire, which must be kept burning during the whole enchantment process, giving birth to the mythical Phoenix (Faerie Might 25). The only known lab text requires the ashes of the old Phoenix.
Base 10, +2 Sun, +4 levels Constant, +25 levels Might
Or
The Hermetic Prometheus.
MuCo 45
Animates a creature (Size+2) made of multiple human corpses stitched together (Faerie Might 6). As designed by Mary Shelley of Merinita. 
Base 20, +2 Sun, +1 Size, +4 level Constant, +6 levels Might.
Now, for something weird: the Corpus guidelines say you can't turn a living person into a faerie. But what about a Bjornaer magus? 
edit: fixed levels.
Interesting. I play a Bjornaer myself, so stay away from me!! 
E.
Also note that, although it is a constant mystical effect, since the resulting faeries have Might, they do not get warped. Whether a hermetic dispelling spell would destroy them is subject to discussion.
Come on, the tattoo design for Fruny's Fetters for the Flighty Otter is positively delightful. I'm sure you'll love it. And all I ask in exchange is seven years of servitude under Faerie Chains of the Familiar Slave. A small price for immortality as a Faerie, isn't it? Do we have a Bargain? Only a Fool would say no. Of course, I'll have to ask you not to try to return to human form in the meantime: while the Fetters would be held until you returned to animal form, I would have to cast Faerie Chains all over again. That would be poor manners on your part.
Fruny's Fetters for the Flighty Otter
MuAn 39
Base 10, +2 Sun, +4 levels Constant, +15 levels Might
Hmm... I do believe that he would retain his ability to change shape, and once he did, the spell would be broken. 
So I'm safe! : 
I hope...
But think of the torture.. a Bjornaer, changed into a faerie! Most Bjornaer have a strong dislike for anything faerie...
E.
Which is why there is an explicit term in our bargain asking you not to do it, and is enforced by Faerie Chains of the Familiar Slave.
Well, all I have to do is add a linked trigger and the spell would be in effect anytime your magus takes on his heartbeast form.
There is no escape, unless you are kissed at dawn by a green-eyed virgin, only then will I be undone. 
Come on, seven years of servitude is nothing.
I don't read it that way. Some Bjornaer have a strong dislike for what Quendalon has done, most Bjornaer prefer "natural" nature to faerie, but I don't really see them in general as having an aversion against all things faerie. I rather think they're just not interested.
Well, my Bjornaer is a very good friend with a Merinita he shares Covenant with. They both have the Carefree flaw, my character because of his heartbeast and the Merinita because he's a panflute playin' half satyr with a passion for the opposite sex. So we don't care much for any grudges our Houses might have.
E.