Review on Bellroy Key Cover Plus 2Nd Edition (Leather Bifold Key Organizer) - Graphite by Matt Welch

You may have to carefully poke a hole in the key to get it big enough, but most keys will fit just fine. I have a fairly complete workshop, but I must warn you that drilling a hole in a key can be a little dangerous. Unless you're very good with tools, stick to a keycap to hold keys with holes big enough to attach a stem to an elastic cord. Rather than a metal pin or screw like many key organizers, the keyhole has an elastic cord that attaches to a metal rod (requires a minimum 7/32" diameter hole. I'm not sure the strength of the cord). . , but time will tell. I carefully ground the holes on each key so as not to cut the cord. If the cord is strong then the key case is a very compact way to carry up to 8 keys without practically protruding in your pocket.