I remember that when Silvery Scales of the Knight was brought to 5th Ed, it was pointed out that the armour had to be made and then put on. That the finesse rolls to have it appear on you were way too high. The SSofK description in HoH:TL p37 mentions putting it on - which to me, means that it appears in front of you, not on you.
There was a discussion on the forum a while back which I think applies to this project.
https://forum.atlas-games.com/t/magic-tools-in-the-laboratory/8469/1
Creating armour with Creo doesn't need much in the way of finesse. Using muto to change air into armour would require a good finesse or you would just end up with pieces of oddly shaped metal.