i imagine some cheap tacky fridge magnets, the kind that come in cereal packets, would be thin enough to cut to shape and glue in. the smaller kickstand magnet isn't as much of an issue (does anyone even use the kickstand? may as well be glued shut!) but if the magnet on the cover goes your memory card stops working. this magnet is how the phone recognises the back cover is attached, and if it doesn't register your n900 will assume you're about to whip out the microsd at any second and won't load it.