So, a Wizard just got their hands on the Planar Binding spell line, and wants to start utilizing it. Said Wizard also likes to be self-sufficient AND is invested in their alignment - which means they don't want to ask other people for help and REALLY don't want to start casting spells of opposed alignment. But in order to Bind a creature of the same alignment, you have to cast a Magic Circle spell of opposed alignment, which even carries an opposed [alignment] descriptor.
After thinking about it for some time, I've realized that the best way to do this by-the-book is to have a magic item that specifically works as a Magic Circle that's turned inside. The question is if there's an item like this already or if I'll have to make a custom one.
I know that there's the Binder-only Seal of the Spirit in Tome of Magic that serves a similar function, but it works strictly for Vestiges.