I was just reading Rival Magic and wondered if you have to use the normal requirements for a specific supernatural ability when using one of these magic items? For example if you use lesser craft magic to make a breath of winter magical device does the person using it still have to do the whole drum ceremony or do they just have to activate the device?
Strictly speaking, it would just provide the effect -- using a Hermetic device does not need the words or gestures of a Hermetic spell, after all. However, as a matter of flavour, you could easily rule that the item should be a drum, and triggered by beating it. This preserves the flavour without greatly reducing the utility of Craft Magic.