Setting up the two rituals took a little time. Enough time for Belladonna to enchant everyone's coin pouch, including her own, with the expanded space enchantment.
They weren't exactly 'bottomless' and to be honest, it was unlikely that her own bag was actually bottomless too. They were simply a portable version of the Tower of Mystica. Putting a large space into a small container, with an extra enchantment for easy access to the contents.
However the size of the space was, for the most part, not based on the actual enchantment itself but on the level of mana that she supplied into it. Which meant that the bags were at the capacity of what she could achieve with a second level source, although it left it open to increasing the size as she grew stronger.
The other limiting factor was the material itself. Much like electricity, mana was restricted by the material it was flowing through. Put too little energy into a strong material, and you would hardly get a reaction.
