Nabbed your idea. Built a prototype in a cardboard Bijoux Terner tie box. Jutting off the lid left the metal/cardboard joint behind so I could wedge the controller into it. Cut a hole out through the side to run the cables out and another for air circulation. Once the magnet is in I'll cover the top with foil to protect it.
I don't think I can overstate how nifty this extension cord is! It goes out quite far and it's probably thin enough to close in a minifridge door.
Gonna need a magnet though. And a stirbar. And a flask.
I'll be looking for less flammable boxes while I get those things. Has anyone heard of stirplates or these USB fans catching on fire from prolonged use?