well my Voltcraft IPC-1L is cooking around when i give him 700mA load on 4 AAs. The Batterys will still get warm. but the damn bcp is cool now, even with this low rpm that i get at 3v. This think schould work for every Version. IPC-1 BC-700 BC-1000 Not sure about the BC-4000.Fan: 50x50x11,5mm It also have to run with only 3v, so get a 12v fan with high rpm. Use normal PC Fan Screws. If you want to use this think on a other version than IPC-1L take mesurese of the stl or print the test.stl. i dont know if a second fan will bring you something, but there is enogh space for two....so why not. You also schould put some kind of feltsticker (not sure about this word. my enlish sucks, yeahyeah i know...) :D