Key holder tube

Hello all. I need a straightforward metal tube to hold an emergency key, with the key attached to the tube via a cable tie or similar fastener. The design should allow for easy access while keeping things visible. It would also be great if someone couldn’t easily take a good look at the key without cutting through the cable tie—useful when you need to copy it. I believe Thumper posted about something like this on her blog, but I’ve lost track of it. Thanks so much for your assistance!