Was just looking at the SRD and thinking, this is a spell that looks pretty workable to add to PotM with a custom script:
Bless Water
Transmutation [Good]
Level: Clr 1, Pal 1
Components: V, S, M
Casting Time: 1 minute
Range: Touch
Target: Flask of water touched
Duration: Instantaneous
Saving Throw: Will negates (object)
Spell Resistance: Yes (object)
This transmutation imbues a flask (1 pint) of water with positive energy, turning it into holy water.
Material Component
5 pounds of powdered silver (worth 25 gp).
This spell would basically work by converting one flask of Water IG into one flask of holy water, deducting 25 GP. (If the caster has less than 25 GP when casting, the spell fails.)
Adding this spell would be nice since it would mean that Clerics, especially those of differing deities from the ones in the setting, could produce their own holy water without having to resort to the slightly strange behaviour of buying stuff that's obviously been blessed by another deity.
I don't think this can be used to make any profit, since most NPC sellers sell the stuff at the inflated rate of around 50 gp anyway... though I don't know what rate a PC merchant could get selling this stuff. (But then if crafted holy water is marked as a plot item, I believe it couldn't be sold, so hopefully that shouldn't be an issue...)
If this isn't acceptable, it might be fun to add a way of turning silver ingots into silver powder, thus requiring said silver powder to be a pre-requisite to casting the spell -- effectively adding Holy Water as part of the craft cycle.
