I could see it working a bit like this: you use Thaumaturgy to summon up an amount of power, with a certain purpose, for this example: a sword to do battle with. You summon the magical power, but instead of using ectoplasm to give it form, you leave it as a tattoo upon your body. Now, when you need it, you pull the tattoo of your skin, releasing the magical power and forming the sword for a scene. Afterwards, the power dissipates.
This way, you would be able to become very versatile, but you do not really create the 'not-an-item enchanted item', because it lasts only a scene. (Of course, you could more power into the item to keep it solid, by taking mental stress, I guess.)
As for mechanics, I'm not your man