New Spell: Charging Rack

[Pursuivant]

I'd charge energy and $ for the item based on Number of Sockets + Total Powerstone Energy each socket can hold.

If you want to complicate the spell, you could increase energy and $ cost based on each halving of the 2-yard rule for Powerstone charging.

You could also rule that there's no cost increase as long as the item's total area is the same as that needed to charge all the Powerstones it contains individually. For example, you could have "recharging conduits" running all through a building, leading to a safe holding multiple Powerstones.