I've been rereading the Jerbiton chapter of HoHMC. I'm wondering over the mechanics of prop use.
The text says "The use of props slows ceremonial casting", but doesn't provide any such penalty. I'm wondering if such a penalty is appropriate at all. If so, should it depend on prop size?
Another issue is the fitting of the prop to the casting. The description of Carmine's and Andru's props indicate that some kind of correspondence must exist for the props to be useful. I'm thinking simply requiring that the Shape & Material Bonus would suit the magic being cast.
Or you could go for a straight 15 minutes of set-up time, arguing that even small props must be prepared or placed precisely for the specific spell/effect the caster has in mind.
Sounds OK. Or you can hand-wave it until you suddenly decree that, for that one spell they want to cast, they really need a live chicken that they'll pluck while casting the spell. Then let them deal with that.
Mmm. My issue with the ceremonial props is that their size is more important than their significance. I'm currently arguing for a house rule to just use the S&M bonus of your major prop, capped at MT and possibly also by time taken to set it up. That way you keep preparation as key without trying to find some way for "a fire garnet amulet, set in a steel chain" to be used in all your Ignem-related ceremonies and also make the role-playing of using appropriate props more important.
'Course, once you get to that point then having Potent Magic be a mystery and apply only to a select area of spells gets iffy. (I'm not a Potent Magic fan - I feel, aside from the bonus to casting and creation, that it detracts power and flexibility from Hermetic magic by returning, with additional restrictions, something which used to be there anyway. The idea's good; the implementation leaves much to be desired.)
Then let them deal with that.